Photolithographic patterning of organic electronic devices

ABSTRACT

A method of making an OLED device includes providing a first undercut lift-off structure over the device substrate having a first array of bottom electrodes. Next, one or more first organic EL medium layers including at least a first light-emitting layer are deposited over the first undercut lift-off structure and over the first array of bottom electrodes. The first undercut lift-off structure and overlying first organic EL medium layer(s) are removed by treatment with a first lift-off agent comprising a fluorinated solvent to form a first intermediate structure. The process is repeated using a second undercut lift-off structure to deposit one or more second organic EL medium layers over a second array of bottom electrodes. After removal of the second undercut lift-off structure, a common top electrode is provided in electrical contact with the first and second organic EL medium layers.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is being filed on Jul. 31, 2015, as a PCT InternationalPatent application and claims the benefit of U.S. ProvisionalApplication No. 62/031,888, filed on Aug. 1, 2014, the entire disclosureof which is hereby incorporated herein by reference. This application isalso related to PCT International Applications with Attorney Docket Nos.16480.0026WOU1, 16480.0033WOU1 and 16480.0030WOU1, filed on even dateherewith and claiming the benefit of U.S. Provisional Applications Nos.62/031,891 (filed on Aug. 1, 2014), 62/031,897 (filed on Aug. 1, 2014)and 62/096,582 (filed on Dec. 24, 2014), and 62/031,903 (filed on Aug.1, 2014), respectively.

BACKGROUND

1. Field of the Disclosure

The present disclosure relates to photolithographic patterning oforganic, electronic and organic electronic devices. The disclosedmethods and materials are particularly useful for patterning OLEDdevices.

2. Discussion of Related Art

Organic electronic devices may offer significant performance and priceadvantages relative to conventional inorganic-based devices. As such,there has been much commercial interest in the use of organic materialsin electronic device fabrication. For example, displays based on organiclight-emitting diode (OLED) technology have recently gained popularityand offer numerous advantages over many other display technologies.Although solution-deposited OLED materials have been developed, thehighest-performing OLED devices typically use vapor-deposited thin filmsof active organic materials.

A key challenge for full-color OLED displays is patterning the array ofred, green and blue pixels. For vapor-deposited OLEDs, a fine metal maskhaving openings corresponding to the fineness of the desired pattern isconventionally used. However, a vapor deposited film builds up on themask which may eventually narrow the mask openings or cause deformingstresses on the mask. Therefore, it is necessary to clean the mask aftera certain number of uses, which is disadvantageous from the viewpoint ofmanufacturing costs. In addition, when a fine metal mask is increased insize to accommodate larger substrates, the positional accuracy of themask openings becomes much more difficult, both from the standpoint ofinitial alignment and then maintaining the alignment during depositiondue to thermal expansion issues. Positional accuracy may be improved toa degree by enhancing the stiffness of a frame of the mask, but thisincrease the weight of the mask itself causes other handlingdifficulties.

Thus, a need exists for cost-effective patterning of organic electronicdevices such as OLED devices, and particularly those having emissivepattern dimensions of less than about 100 μm.

SUMMARY

The authors have demonstrated OLED devices having photolithographicallypatterned red, green and blue emissive areas separated by 4 μm andhaving an aperture ratio of greater than 60%.

In accordance with the present disclosure, a method of making an OLEDdevice includes:

providing a device substrate having a first array of bottom electrodesand a second array of bottom electrodes; providing a first undercutlift-off structure over the device substrate having a first pattern ofopenings corresponding to the first array of bottom electrodes;depositing one or more first organic EL medium layers including at leasta first light-emitting layer over the first undercut lift-off structureand over the first array of bottom electrodes; removing the firstundercut lift-off structure and overlying first organic EL mediumlayer(s) by treatment with a first lift-off agent comprising afluorinated solvent to form a first intermediate structure; providing asecond undercut lift-off structure over the first intermediate structurehaving a second pattern of openings corresponding to the second array ofbottom electrodes; depositing one or more second organic EL mediumlayers including at least a second light-emitting layer over the secondundercut lift-off structure and over the second array of bottomelectrodes; removing the second undercut lift-off structure andoverlying second organic EL medium layer(s) by treatment with a secondlift-off agent comprising a fluorinated solvent to form a secondintermediate structure; and providing a common top electrode inelectrical contact with the first and second organic EL medium layers.

In another aspect of the present disclosure, a full color OLED displayincludes: a substrate having a display region, the display regionincluding an array of first, second and third organic EL elements, eacharray having individually patterned light-emitting layers for emissionof differently colored light, wherein each of the first organic ELelements is spaced 4 μm or less from a second or third organic ELelement and a combined emissive area of all of the first, second andthird organic EL elements is at least 60% of a total area occupied bythe display region.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is cross sectional view of a representative OLED device;

FIG. 2 is a flow chart depicting the steps in an embodiment of thepresent disclosure;

FIG. 3 is a series (3A-3K) of cross-sectional views depicting variousstages in the formation of an active matrix OLED device according to anembodiment of the present disclosure;

FIG. 4 is a flow chart depicting the steps in an embodiment of thepresent disclosure:

FIG. 5 is a series (5A-5E) of cross-sectional views depicting variousstages in the formation of an undercut lift-off structure according toan embodiment of the present disclosure;

FIG. 6 is a flow chart depicting the steps in an embodiment of thepresent disclosure;

FIG. 7 is a cross-sectional view of an active matrix OLED deviceaccording to an embodiment of the present disclosure;

FIG. 8 is a cross-sectional view depicting a stage in the formation ofan active matrix OLED device according to an embodiment of the presentdisclosure, wherein a top electrode is deposited so as to cover theedges of organic EL medium layers;

FIG. 9 is a cross-sectional view depicting a stage in the formation ofan active matrix OLED device according to an embodiment of the presentdisclosure, wherein a vapor-deposited layer of a fluorinated material isprovided;

FIG. 10A is a cross-sectional view depicting a defective active matrixOLED device wherein the top common electrode has poor electricalconnectivity between individual OLED devices:

FIG. 10B is a cross-sectional view depicting an active matrix OLEDdevice according to an embodiment of the present disclosure including apatterned fluorinated dielectric structure;

FIG. 11 is a flow chart depicting the steps in an embodiment of thepresent disclosure;

FIG. 12 is a series (12A-12J) of cross-sectional views depicting variousstages in the formation of an active matrix OLED device according to anembodiment of the present disclosure;

FIG. 13 is a series (13A-13D) of cross-sectional views depicting variousstages in the formation of an organic device according to an embodimentof the present disclosure;

FIG. 14 is a series (14A-14B) of cross-sectional views depicting variousstages in the formation of an active matrix OLED device according to anembodiment of the present disclosure; and

FIG. 15 is a series (15A-15C) of views depicting various stages andviews in the formation of a test device according to an embodiment ofthe present disclosure.

DETAILED DESCRIPTION

It is to be understood that the attached drawings are for purposes ofillustrating the concepts of the disclosure and may not be to scale.

A feature of the present disclosure is the use of “orthogonal”photoresist structures and processing agents that are compatible withsensitive organic electronic devices and materials such as OLED devicesand materials, i.e., they are chosen to have low interaction withsensitive device layers that are not intended to be dissolved orotherwise damaged. Conventional photoresist materials typically useharsh organic solvents and often strongly caustic developers that caneasily damage one or more layers of an OLED device. Particularly usefulorthogonal photoresist structures and processing agents includefluorinated polymers or molecular solids and fluorinated solvents. Someorthogonal photoresist structures and systems are disclosed in U.S.patent application Ser. Nos. 12/864,407, 12/994,353, 14/113,408, and14/291,692, the contents of which are incorporated by reference. Thephotoresist structures of the present disclosure may optionally have anundercut profile, which can be advantageous in so-called “lift-off”photolithographic patterning. Photoresist structures intended forlift-off patterning may also be referred to herein as lift-offstructures. Undercut lift-off structures are preferred wherein a topportion is wider than a base portion adjacent to a substrate. Thephotoresist structure may be a single layer (e.g. an invertedtrapezoid), a bilayer or multilayer structure. It is preferred that atleast the layer or portion of the photoresist structure in contact withthe sensitive organic electronic device is a fluorinated polymer ormolecular solid provided, e.g., from a fluorinated coating solvent or byvapor deposition. Orthogonality can be tested by, for example, immersionof a device comprising the material layer of interest into a targetcomposition prior to operation (e.g., into a coating solvent, adeveloping agent, a lift-off agent, or the like). The composition isorthogonal if there is no serious reduction in the functioning of thedevice.

Certain embodiments disclosed in the present disclosure are particularlysuited to the patterning of solvent-sensitive, active organic materials.Examples of active organic materials include, but are not limited to,organic electronic materials, such as organic semiconductors, organicconductors, OLED (organic light-emitting diode) materials and organicphotovoltaic materials, organic optical materials and biologicalmaterials (including bioelectronics materials). Many of these materialsare easily damaged when contacted with organic or aqueous solutions usedin conventional photolithographic processes. Active organic materialsare often coated to form a layer that may be patterned. For some activeorganic materials, such coating can be done from a solution usingconventional methods. Alternatively, some active organic materials arecoated by vapor deposition, for example, by sublimation from a heatedorganic material source at reduced pressure. Solvent-sensitive, activeorganic materials can also include composites of organics andinorganics. For example, the composite may include inorganicsemiconductor nanoparticles (quantum dots). Such nanoparticles may haveorganic ligands or be dispersed in an organic matrix. The presentdisclosure is particularly directed towards patterning of OLED devices,but the concepts and methods disclosed herein can be applied to otherorganic electronic or bioelectronic devices.

OLED Structures

Many different types of OLED device structures have been developed overthe years. Essentially, an OLED device includes at a minimum an anodefor injecting holes, a cathode for injecting electrons and an organic ELmedium sandwiched between the electrodes wherein the holes and electronscombine to produce light emission. OLED devices are often provided on asubstrate. The electrode adjacent to a substrate is typically referredto as the first or bottom electrode. The electrode spaced away from thesubstrate by the organic EL medium is typically referred to as thesecond or top electrode. A common structure (“standard structure”)includes an anode as the bottom electrode provided on a substrate withsubsequent organic layers deposited over the anode and finally a cathodedeposited over the organic layers to form the top electrode. An“inverted structure” is just the reverse and has a cathode as the bottomelectrode provided on a substrate with subsequent organic layersdeposited over the cathode and finally an anode deposited over theorganic layers to form a top electrode. A “bottom-emitting” OLEDtypically includes a transparent or translucent bottom electrode and areflective or light absorbing top electrode structure. That is, light isdirected through the device substrate. A “top-emitting” OLED includes atransparent or translucent top electrode and a reflective or lightabsorbing bottom electrode structure. That is, light is directed awayfrom the device substrate. A “transparent” OLED has transparent ortranslucent top and bottom electrodes.

A non-limiting example of an OLED device 10 is shown in FIG. 1 andincludes anode 11, hole-injecting layer (HIL) 12, hole-transportinglayer (HTL) 13, electron-blocking layer (EBL) 14, light-emitting layer(LEL) 15 (sometimes referred to in the art as an emissive layer or EML),hole-blocking layer (HBL) 16, electron-transporting layer (ETL) 17,electron-injecting layer (EIL) 18 and cathode 19. The layers between theanode and cathode are often collectively referred to as the organic ELmedium 20. There are many other OLED layer architectures known in theart having fewer or additional layers and there can be overlap in layerfunctionality. For example, if an EBL is used, it typically also hashole-transporting properties in addition to electron-blockingproperties. An HBL, if used, typically has electron-transportingproperties. The LEL might have predominantly hole-transporting orelectron-transporting properties, or it might have both. There can bemultiple light emitting layers. So-called “tandem” architecture is knownthat includes one or more charge separation layers betweenlight-emitting stacks that can double current efficiency.

Some non-limiting examples of materials useful for OLED devices arediscussed below. Although the emphasis is on organic EL medium materialsthat can be vapor deposited, certain embodiments of the presentdisclosure may instead use solution deposited OLED materials. A fewnon-limiting examples of OLED material and structures can be found inU.S. Pat. No. 8,106,582 and U.S. Pat. No. 7,955,719, the entire contentsof which are incorporated by reference.

When EL emission is viewed through the anode, the anode should besubstantially transparent to the emission of interest. The term“transparent” herein means that at least 30% of emitted light istransmitted, preferably at least 50%. Common transparent anode materialsused in the present disclosure are indium-tin oxide (ITO), indium-zincoxide (IZO), and tin oxide, but other metal oxides can work including,but not limited to, aluminum- or indium-doped zinc oxide,magnesium-indium oxide, and nickel-tungsten oxide. In addition to theseoxides, metal nitrides such as gallium nitride, and metal selenides suchas zinc selenide, and metal sulfides such as zinc sulfide, can be usedas the anode. For applications where EL emission is viewed only throughthe cathode electrode, the transmissive characteristics of the anode areimmaterial and many conductive materials can be used, regardless iftransparent, opaque, or reflective. Example conductors for the presentdisclosure include, but are not limited to, gold, iridium, molybdenum,palladium, and platinum. Unless unique HIL materials are used, typicalanode materials have a work function of at least 4.0 eV.

If EL emission is viewed through the cathode, it must be transparent ornearly transparent. For such applications, metals must be thin(preferably less than 25 nm) or one may use transparent conductiveoxides (e.g. indium-tin oxide, indium-zinc oxide), or a combination ofthese materials. Some non-limiting examples of optically transparentcathodes have been described in more detail in U.S. Pat. No. 5,776,623.If EL emission is not viewed through the cathode, any conductivematerial known to be useful in OLED devices may be selected, includingmetals such as aluminum, molybdenum, gold, iridium, silver, magnesium,the above transparent conductive oxides, or combinations of these.Desirable materials promote electron injection at low voltage and haveeffective stability. Useful cathode materials often contain a low workfunction metal (<4.0 eV) or metal alloy. Cathode materials can bedeposited, for example, by evaporation, sputtering, or chemical vapordeposition.

The HIL can be formed of a single material or a mixture of materials.The hole-injecting layer may be divided into several layers havingdifferent composition. The hole-injecting material can serve to improvethe film formation property of subsequent layers and to facilitateinjection of holes into the hole-transporting layer. Suitable materialsfor use in the hole-injecting layer include, but are not limited toporphyrin and phthalocyanine compounds as described in U.S. Pat. No.4,720,432, thiophene-containing compounds, phosphazine compounds, andcertain aromatic amine compounds. The HIL may include an inorganiccompound such as a metal oxide (e.g., molybdenum oxide), metal nitride,metal carbide, a complex of a metal ion and organic ligands, and acomplex of a transition metal ion and organic ligands. Suitablematerials for use in the hole-injecting layer may includeplasma-deposited fluorocarbon polymers (CFx) as described in U.S. Pat.No. 6,208,075, certain hexaazatriphenylene derivatives as described inU.S. Pat. No. 6,720,573 B2 (e.g. hexacyanohexaazatriphenylene) ortetracyanoquinone derivatives such as F4TCNQ. The hole-injecting layercan also be composed of two components: for example, an aromatic aminecompound, doped with a strong oxidizing agent, such asdipyrazino[2,3-f:2′,3′-h]quinoxalinehexacarbonitrile, F4TCNQ, or FeCl3.

The HTL can be formed of a single or a mixture of organic or inorganicmaterials and may be divided into several layers. The hole-transportinglayer most commonly includes a tertiary aryl amine, e.g., a benzidine ora carbazole, but instead (or in addition) may comprise a thiophene, orother electron-rich material. EBL materials (if used) are generallyselected from the same group as HTL materials and have an electronconduction band significantly higher in energy (more difficult toreduce) than the overlying LEL thereby creating a barrier to furtherelectron transport.

The LEL commonly includes a host material and a light-emitting dopant.Injected holes and electrons recombine in the LEL. Hosts include HTLmaterials, ETL materials, a mixture of HTL and ETL materials orambipolar materials readily capable of transporting holes and electrons.Examples of common hosts for singlet emission include polycyclicaromatic compounds such as anthracene derivatives. Examples of commonhosts for triplet emission include carbazole compounds and aromaticamines. A wide variety of light-emitting dopants are known and are usedto provide the desired emission wavelength by harvesting excitonscreated from the electron/hole charge injection. Many common singletemitting dopants are aromatic organic compounds whereas many commontriplet emitting dopants are metal complexes of iridium or platinum.

The ETL can be formed of a single or a mixture of organic or inorganicmaterials and may be divided into several layers. Common ETL materialsinclude metal oxine chelates such as Alq, phenanthroline derivativessuch as BCP, triazenes, benzimidazoles, triazoles, oxadiazoles, silanecompounds such as silacyclopentadiene derivatives, and boranederivatives. HBL materials (if used) are generally selected from thesame group as ETL materials and have hole conduction band significantlylower in energy (more difficult to oxidize) than the underlying LELthereby creating a barrier to further hole transport.

The EIL may include an ETL material plus a reducing dopant at or nearthe interface between the cathode and ETL. The reducing dopant can beorganic, inorganic, or metal complexes. Common reducing dopants includealkali metals such as Cs or combinations of alkali metals. The EIL mayinclude an alkali or alkaline metal complex, salt or oxide (e.g.,lithium quinolate, LiF, CaO) that forms a reducing dopant upondeposition of a cathode material such as aluminum.

OLED Deposition

There are many ways to deposit organic EL medium materials onto asubstrate including, but not limited to, solution coating, vapordeposition, and transfer from a donor sheet. In certain embodiments ofthe present disclosure at least some of the organic OLED layers bedeposited by vapor deposition means, e.g., physical vapor deposition ina reduced pressure environment. In some embodiments, most or all of theorganic EL medium layers are provided by vapor deposition.

Many types of vapor deposition equipment are suitable. Such equipmentmay use point sources, linear sources, vapor-injection sources, carriergas-assisted sources (OVPD) and the like. In some embodiments, the vaporplume is preferably highly directional to achieve a controlledline-of-site deposition through a patterned photoresist structure aswill be shown later.

OLED Devices/Backplanes

There is no particular limitation on the type of OLED device that may befabricated based on methods of the present disclosure, so long as somepatterning is intended. The present methods are especially directed tofull color OLED displays such as active matrix OLED (AMOLED) and passivematrix OLED (PMOLED), but the methods may be used to prepare OLEDlighting and signage. OLED device substrates may be rigid or flexible.Support materials include, but are not limited to, glass, polymers,ceramics and metals, and composites or laminates thereof.

AMOLED backplanes typically include an array of independentlyaddressable first (bottom) electrodes that are connected to thin filmtransistor (TFT) circuitry provided over a substrate typically in amultilayer structure. The TFT may be based on Si, metal oxide or organicsemiconductors (OTFT). In addition to the semiconductors, dielectricsand conductors are used to prepare structures that form the transistors,capacitors, wiring . . . etc. as is known in the art.

OLED Patterning

FIG. 2 is a flow diagram showing steps for forming a three-color (e.g.RGB) active matrix OLED device according to an embodiment of the presentdisclosure. FIGS. 3A through 3K show portions of these steps in crosssectional form. In step 101, a first lift-off structure (e.g. anundercut lift-off structure) is formed over an OLED substrate. Thelift-off structure has an array of openings corresponding to a firstarray of bottom electrodes. The bottom electrodes may serve as anodes aspart of a “standard structure” OLED or serve as cathodes as part of an“inverted structure” OLED. In a preferred embodiment, the bottomelectrodes are already formed as part of the OLED substrate, butoptionally, the bottom electrodes may be formed or further modified bydepositing one or more desired anode or cathode materials through thearray of openings of the lift-off structure (not shown in FIG. 2).

FIG. 3A shows an embodiment of an OLED substrate 200 or backplane havinga support 201 (e.g., flexible or non-flexible glass, plastic orceramic), a TFT layer portion 202 (which may include multiple layers ofwiring, dielectric and semiconductor materials), a first bottomelectrode 210, a second bottom electrode 220, a third bottom electrode230 and an electrode-separating dielectric 203. The first, second andthird bottom electrodes each represent one bottom electrode in a first,second and third array of bottom electrodes, respectively, allindependently addressable. That is, the first array of bottom electrodesforms a portion of a first array of independently addressable first OLEDdevices, the second array of bottom electrodes forms a portion of asecond array of independently addressable second OLED devices and so onas needed. Although not shown, the electrode-separating dielectric oftenextends above and slightly over the edges of the bottom electrodes andmay serve to help define the functional emissive area of thecorresponding OLED device. Also not shown, the substrate may furtherinclude common organic EL medium layers that will make up a portion ofeach organic EL element. For example, the substrate may include a commonHIL and HTL.

FIG. 3B shows a first lift-off structure 211 having an opening 215corresponding to the first bottom electrode. In the embodiment shownhere, the first lift-offstructure 211 is a bilayer of first materiallayer 212 and first patterned photoresist layer 213. An undercut region214 is formed in layer 212. The first lift-off structure 211 may insteadbe a single layer or have more than two layers. Lift-off structures arediscussed in more detail later.

Referring again to FIG. 2, optional (but preferred) step 103 includescleaning residue from the first array of bottom electrodes (or from anyoptional common organic EL medium layers). This can be done usingappropriate solvents, or preferably, using “dry etching” methods.Herein, the term “dry etchant” is used broadly and refers to any usefulgaseous material possessing energy sufficient to clean a target area.Dry etching includes, but is not limited to, glow discharge methods(e.g., sputter etching and reactive ion etching), ion beam etching(e.g., ion milling, reactive ion beam etching, ion beam assistedchemical etching) and other “beam” methods (e.g., ECR etching anddownstream etching), all of which are methods known in the art. Somecommon dry etchants include oxygen plasma, argon plasma, UV/ozone, CF₄and SF₆, and various combinations. Alternatively a substantiallynon-oxidizing plasma may be used, e.g., one including hydrogen and anon-oxidizing gas such as nitrogen or helium.

Referring to FIG. 2 and FIG. 3C, the first organic EL medium layer(s)are deposited in step 105 followed by deposition of the first topelectrode in step 107 over the first organic EL medium layers. A portionof the first organic EL medium layers 216′ is deposited over thelift-off structure whereas another portion of the first organic ELmedium layers 216 goes through the opening 215 and is deposited on thefirst array of bottom electrodes. With respect to the top electrode, aportion of the first top electrode 217′ is deposited over the lift-offstructure and onto organic EL medium layers 216′ whereas another portionof the first top electrode 217 goes through opening 215 and is depositedonto first organic EL medium layers 216. Not shown, but if the substrateincluded any optional common organic EL medium layers as discussedabove, the first organic EL medium layers 216 would include thosenecessary to finish the OLED stack over the first array of bottomelectrodes.

In step 109 the lift-off structure is removed along with the overlyingfirst organic EL medium layers 216′ and first top electrode 217′. In anembodiment, this is done by providing a solvent that dissolves the firstmaterial layer 212 but that is orthogonal to the patterned photoresist,organic EL medium materials and cathode. This detaches the firstpatterned photoresist 213 and overlying layers 216′ and 217′, therebyforming a first intermediate structure 218 as shown in FIG. 3D having afirst array of OLED devices, e.g., red-emitting OLEDs, each having abottom electrode 210, organic EL medium layers 216 and top electrode217. Alternatively, rather than dissolving the first material layer, thelift-off solvent may swell the lift-off structure thereby causing itsdelamination or otherwise affect the adhesion between the substrate andthe lift-off structure.

Steps 101 through 109 are basically repeated two more times in steps 111through 119 and steps 121 through 129, but with different sets oforganic EL medium layers (226 and 236, FIGS. 3F and 3I) to form secondand third arrays of OLED devices, e.g., green and blue.

In step 111 of FIG. 2, a second lift-off structure is formed over thefirst intermediate structure. The second lift-off structure has an arrayof openings corresponding to a second array of bottom electrodes. FIG.3E shows a second lift-off structure 221 having an opening 225corresponding to the second bottom electrode. In the embodiment shownhere, the second lift-off structure 221 is again a bilayer of secondmaterial layer 222 and second patterned photoresist layer 223. Anundercut region 224 is formed in layer 222. The second lift-offstructure 221 may instead be a single layer or have more than twolayers. The materials and methods used to form second lift-off structure221 may be the same as or different from those used to form the firstlift-off structure 211.

Step 113 in FIG. 2 indicates an optional (but preferred) step ofcleaning residue from the second array of bottom electrodes using one ofthe methods previously described with respect to step 103. The residuecleaning method may the same as or different from step 103.

Referring to FIG. 2 and FIG. 3F, the second organic EL medium layers aredeposited in step 115 followed by deposition of the first top electrodein step 117 over the second organic EL medium layers. Although notlimiting, in a preferred embodiment, the second organic EL medium layersare different from the first organic EL medium layers, e.g., to providea different emission color. The second top electrode may be the same asthe first top electrode, but it may also be different, e.g., in order toachieve some desired charge injection or property. A portion of thesecond organic EL medium layers 226′ is deposited over the lift-offstructure whereas another portion of the second organic EL medium layers226 goes through the opening 225 and is deposited on the second array ofbottom electrodes. With respect to the top electrode, a portion of thesecond top electrode 227′ is deposited over the lift-off structure andonto second organic EL medium layers 226′ whereas another portion of thesecond top electrode 227 goes through opening 225 and is deposited ontosecond organic EL medium layers 226.

In step 119 the lift-off structure is removed along with the overlyingsecond organic EL medium layers 226′ and second top electrode 227′,e.g., by providing a solvent that dissolves the second material layer222, in a manner analogous to that previously described for step 109.Removal of the second lift off structure forms a second intermediatestructure 228 as shown in FIG. 3G having a first array of OLED devices,e.g., red-emitting OLEDs, and a second array of OLED devices, e.g.,green-emitting OLEDs, each having a bottom electrode 220, organic ELmedium layers 226 and top electrode 227.

In step 121 of FIG. 2, a third lift-off structure is formed over thesecond intermediate structure. The third lift-off structure has an arrayof openings corresponding to a third array of bottom electrodes. FIG. 3Hshows a third lift-off structure 231 having an opening 235 correspondingto the third bottom electrode. In the embodiment shown here, the firstlift-off structure 231 is again a bilayer of third material layer 232and third patterned photoresist layer 233. An undercut region 234 isformed in layer 232. The third lift-off structure 231 may instead be asingle layer or have more than two layers. The materials and methodsused to form third lift-off structure 231 may be the same as, ordifferent from, those used to form the first or second lift-offstructures.

Step 123 in FIG. 2 indicates an optional (but preferred) step ofcleaning residue from the third array of bottom electrodes using one ofthe methods previously described with respect to step 103. The residuecleaning method may the same as or different from step 103.

Referring to FIG. 2 and FIG. 3I, the third organic EL medium layers aredeposited in step 125 followed by deposition of the third top electrodein step 127 over the third organic EL medium layers. Although notlimiting, in a preferred embodiment, the third organic EL medium layersare different from the first and second organic EL medium layers, e.g.,to provide a different emission color. The third top electrode may bethe same as the first or second top electrode, but it may also bedifferent, e.g., in order to achieve some desired charge injection orproperty. A portion of the third organic EL medium layers 236′ isdeposited over the lift-off structure whereas another portion of thethird organic EL medium layers 236 goes through the opening 235 and isdeposited on the third array of bottom electrodes. With respect to thetop electrode, a portion of the third top electrode 237′ is depositedover the lift-offstructure and onto third organic EL medium layers 236′whereas another portion of the third top electrode 237 goes throughopening 235 and is deposited onto third organic EL medium layers 236.

In step 129 the third lift-off structure is removed along with theoverlying third organic EL medium layers 236′ and third top electrode237′, e.g., by providing a solvent that dissolves the third materiallayer 232, in a manner analogous to that previously described for step109. Removal of the third lift off structure forms a third intermediatestructure 238 as shown in FIG. 3J having a first array of OLED devices.e.g., red-emitting OLEDs, and a second array of OLED devices, e.g.,green-emitting OLEDs, and a third array of OLED devices, e.g.,blue-emitting, each having a bottom electrode 230, organic EL mediumlayers 236 and top electrode 237.

Referring to FIG. 2 and FIG. 3K, step 131 includes depositing a commontop electrode 240 over the first, second and third arrays of OLEDdevices thereby electrically connecting the first, second and third topelectrodes and forming active matrix OLED device 250. Relative to thefirst, second and third top electrodes, the material used for the commontop electrode may be the same or different. Prior to depositing thecommon top electrode, the top electrodes may be treated to improveelectrical contact with the common top electrode. This can help overcomecontact resistance introduced by metal oxide or thin polymer residuethat may be present on the top electrodes. For example, the topelectrodes may be treated with a low work function metal, e.g., analkali metal, an alkaline metal or an alkaline earth metal.Alternatively, treatment may include a reducing gas environment, e.g. agas environment including hydrogen. Alternatively, treatment may includea substantially non-oxidizing plasma. e.g. one including hydrogen andanother non-oxidizing gas such as nitrogen or helium. Alternatively,treatment may include contact with a cleaning agent having a chemicalcomposition different from the lift-off agent, the cleaning agentincluding a fluorinated solvent. For example, the cleaning agent mayinclude a fluorinated solvent and a protic solvent such as an alcohol(e.g. IPA) at 15% or less by volume, alternatively 5% or less by volume.Alternatively, the protic solvent may include an organic acid at 5% orless by weight or alternatively 1% or less by weight. Alternatively, thecleaning agent may include a mixture of two fluorinated solvents, e.g.,a mixture of a fluorinated solvent used in the lift-off agent and asecond fluorinated solvent that is more polar or has less fluorinecontent by weight or both.

Lift-Off Structures

The lift-off structure allows separation of “unwanted” overlying activematerials (e.g., OLED materials) in the lift-off patterning process. Inan embodiment, at least a portion of the lift-off structure is solublein a solvent that is orthogonal to the array of OLED devices and thedissolution of this portion enables the separation. In an embodiment,the lift-off structure has a substantially vertical sidewall profile(e.g., 90°-10° relative to the substrate), or preferably, an undercutsidewall profile. The undercut reduces the amount of OLED material thatdeposits on the sidewalls so that the sidewalls remain unblocked to anappropriate lift-off agent. The thickness of the lift-off structuredepends on the particular type of device and intended dimensions, but ingeneral, it is in a range of 0.1 to 10 μm, alternatively in a range of0.2 to 5 μm, or alternatively in a range of 0.5 to 3 μm.

An important requirement of the lift-off structure is that it not harmunderlying device layers, neither in the lift-off structure's formationnor its subsequent processing. In an embodiment, the lift-offstructureincludes a layer of a fluorinated material in contact with one or moreunderlying OLED device layers. In one embodiment, the fluorinatedmaterial is photosensitive and can form the lift-off structure byexposure to radiation and development. Such a material may be a positiveworking (portions exposed to radiation are removed during development)or negative working (portions not exposed to radiation are removedduring development). Non-limiting examples of photosensitive fluorinatedmaterials and systems include those disclosed in U.S. patent applicationSer. Nos. 12/994,353, 14/260,705, 14/291,692, 14/291,767, and 14/539,574the contents of which are incorporated by reference. In an embodiment,the photosensitive fluorinated material is a negative workingphotopolymer provided from a fluorinated solvent, e.g., ahydrofluoroether. In an embodiment, the photosensitive fluorinatedphotopolymer is developed in a developing agent comprising one or morefluorinated solvents, e.g., a hydrofluoroether. In an embodiment, alift-off agent for use with a photosensitive fluorinated photopolymerincludes a fluorinated solvent, e.g., a hydrofluoroether. The action ofthe lift-off agent is to dissolve the photopatterned fluoropolymer oralternatively cause delamination of the photopatterned polymer to thesubstrate, e.g., by swelling or inducing adhesion failure.

It can be challenging to achieve necessary photosensitivity, sidewallprofile and orthogonality in a single layer lift-off structure. Inanother embodiment, the lift-off structure includes multiple layers,e.g., as shown in FIG. 3 and as described in U.S. patent applicationSer. No. 12/864,407, the contents of which are incorporated byreference. In an embodiment, a material layer comprising a fluorinatedmaterial such as a fluorinated molecular solid or fluorinated polymer isprovided over a device substrate that may include an active organicmaterial. The fluorinated material may be vapor deposited (e.g., if amolecular solid) or coated from a highly fluorinated solvent including,but not limited to, a hydrofluoroether or a perfluorinated solvent. Thislayer forms the base of the multi-layer lift-off structure and isdesigned to be chemically inert relative to the underlying devicesubstrate. It does not require photo-active elements such as photoacidgenerators or reactive groups that may, in some cases, harm theunderlying device. The base layer may optionally comprise a lightabsorbing material to protect the underlying device from potentiallyhigh-intensity radiation of the overlying photoresist layer (see below).If so, the light absorbing material is preferably incorporated into basethe layer covalently, e.g., by attaching a light absorbing dye to afluorinated polymer. The base layer is further designed to be readilysoluble in a fluorinated or other orthogonal solvent to enable rapidlift-off as described earlier. Alternatively, the lift-off agent maycause delamination of the base layer from the substrate, e.g., byswelling or inducing adhesion failure.

Over the base layer, e.g., over a fluorinated material layer, aphotoresist layer is applied, e.g., from a coating solvent or bylamination. The photoresist can be a conventional photoresist (positiveor negative tone) coated from, or processed with, solvents that wouldnormally be harmful to the underlying device substrate, but the baselayer blocks penetration of such harmful materials. When exposed toappropriate radiation, and optionally heat, the photoresist transformsin some way to alter its solubility relative to unexposed photoresist.For example, exposure may activate solubility-altering switching groups,induce cross-linking or cause chain scission. The photoresist mayoptionally be a fluorinated photoresist provided from a fluorinatedcoating solvent so long as the underlying base layer retains at leastsome of its structural integrity, i.e., it is not dissolved too quicklyby the coating solvent. Although such fluorinated photoresists may begenerally benign, an additional layer of separation from the photoactivelayer of photoresist can in some embodiments provide extra protection.

A flow diagram for an embodiment of forming a two-layer lift-offstructure is shown in FIG. 4, and in cross-sectional view in FIG. 5.Such lift-off structures may be used in the embodiments described inFIGS. 2 and 3. In step 301, a base layer 311 is formed over devicesubstrate 310. The base layer may undergo subsequent processing stepssuch as curing, drying, surface treatments or the like. In step 303 aphotoresist layer 312 is formed over base layer 311. The photoresistlayer may undergo drying or other steps prior to step 305 wherein thephotoresist layer 312 is exposed to patterned radiation by providing aradiation source 313 and an intervening photomask 314. This forms anexposed photoresist layer 315 having a pattern of exposed photoresistregions 316 and a complementary pattern of unexposed photoresist regions317. In this case the photoresist is a negative tone type, but apositive tone could be used instead. Other methods of photopatterningmay optionally be used, e.g., projection exposure, patterned laserexposure and the like.

Next, as shown in step 307, the exposed photoresist layer is developedwith a developing agent (e.g., an aqueous, alkaline developer if usingmany conventional photoresists), which in this embodiment, removesunexposed photoresist regions 316 to form a first pattern of uncoveredbase layer 318. In step 309, the first pattern of uncovered base layeris removed, for example, by using a fluorinated developing agent such asa hydrofluoroether to form lift-off structure 319 having a first patternof openings 320. In this embodiment, the removal of the base layer formsan undercut region 321. After deposition of active materials, e.g., asdescribed for an OLED device in FIGS. 2 and 3, the structure issubjected to a lift-off agent that dissolves the base layer. Forexample, if the base layer is a fluorinated material, the lift-off agentmay be a fluorinated solvent, including but not limited to,hydrofluoroethers and perfluorinated solvents.

In many embodiments described above, a fluorinated photoresist or afluorinated base layer may be coated or processed (e.g., development orlift-off) using a fluorinated solvent. Particularly useful fluorinatedsolvents include those that are perfluorinated or highly fluorinatedliquids at room temperature, which are immiscible with water and manyorganic solvents. Among those solvents, hydrofluoroethers (HFEs) arewell known to be highly environmentally friendly, “green” solvents.HFEs, including segregated HFEs, are preferred solvents because they arenon-flammable, have zero ozone-depletion potential, lower global warmingpotential than PFCs and show very low toxicity to humans.

Examples of readily available HFEs and isomeric mixtures of HFEsinclude, but are not limited to, an isomeric mixture of methylnonafluorobutyl ether and methyl nonafluoroisobutyl ether (HFE-7100), anisomeric mixture of ethyl nonafluorobutyl ether and ethylnonafluoroisobutyl ether (HFE-7200 aka Novec™ 7200), 3-ethoxy-1,1,1,2,3,4,4,5,5,6,6,6-dodecafluoro-2-trifluoromethyl-hexane (HFE-7500aka Novec™ 7500),1,1,1,2,3,3-hexafluoro-4-(1,1,2,3,3,3,-hexafluoropropoxy)-pentane(HFE-7600 aka PF7600 (from 3M)), 1-methoxyheptafluoropropane (HFE-7000),1,1,1,2,2,3,4,5,5,5-decafluoro-3-methoxy-4-trifluoromethylpentane(HFE-7300 aka Novec™ 7300), 1,2-(1,1,2,2-tetrafluoroethoxy)ethane(HFE-578E), 1,1,2,2-tetrafluoroethyl-1H,1H,5H-octafluoropentyl ether(HFE-6512), 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether(HFE-347E), 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether(HFE-458E), 2,3,3,4,4-pentafluorotetrahydro-5-methoxy-2,5-bis[1,2,2,2-tetrafluoro-1-(trifluoromethyl)ethyl]-furan(HFE-7700 aka Novec™ 7700),1,1,1,2,2,3,3,4,4,5,5,6,6-tridecafluorooctane-propyl ether (TE6O-C3),F(CF₂)₅OCH₃, F(CF₂)₆OCH₃, F(CF₂)₇OCH₃, F(CF₂)₈OCH₂CH₂CH₃,F(CF₂)₂O(CF₂)₄OCH₂CH₃, F(CF₂)₃OCF(CF₃)CF₂OCH₃, (CF₃)₂N(CF₂)₃OCH₃,(C₃F₇)N(CF₂)₃OC₃H₇,

In an embodiment, the lift-off structure (single- or multi-layer type)absorbs or blocks underlying layers from at least 80% of any imagingradiation used in the formation of the lift-off structure.

In an embodiment, the photoresist portion of the lift-off structure isformed using a positive-type of photoresist. In this way, any underlyingOLED devices or structures will not be exposed to potentially harmfulimaging radiation.

Oxygen and Water Sensitivity

OLED devices are known in the art to have poor resistance to oxygen andwater. Of particular concern are low work function cathode materials,the electron-rich dopants in an optional EIL and the interface betweenthe cathode and the ETL or EIL. Referring to FIG. 2, for example, steps105, 115, and 115 (deposit organic EL medium layers) along with steps107, 117, and 119 (deposit top electrodes) may be done under a lowpressure (vacuum) environment that has low oxygen and water. However, insuch case, the substrate will likely be removed from the low pressureenvironment into an ambient environment for other steps relating toremoval (lift-off) of lift-off structures and forming additionallift-off structures. Although one can design equipment for lift-offprocessing (coating, exposure, development, lift-off and the like) undernitrogen or other inert gas, additional precautions can be useful.

In an embodiment, rather than provide the full OLED structure includingindividual top electrodes for each emitting color as shown in FIGS. 2and 3, only organic EL medium layers are provided. In a preferredembodiment, each OLED stack is provided up through at least itsrespective LEL, but does not include an EIL or any layers havingelectron rich dopants such as alkali metal, alkaline metal or alkalineearth metal dopants. For example, the OLED stack may be provided up toand including the HBL. A common cathode layer (and optional commonorganic EL medium layers such as EIL or ETL or both) can be applied atthe end of the process and such common EIL/cathode layers will not beexposed to potential water and oxygen contamination that may arise inthe lift-off related processes. This alternative process flow is shownin FIG. 6 and is in other respects the same as shown in FIG. 2. In FIG.6, steps 401 through 431 correspond to steps 101 through 131 of FIG. 2,respectively. Relative to FIG. 2, the differences in FIG. 6 are: 1) thebottom electrodes are now referred to as bottom anodes; 2) the steps ofdepositing first, second and third top electrodes are absent; and 3) anew step 430 is introduced which has no counterpart in FIG. 2 wherebyone or more common organic EL media layers are optionally deposited overthe third intermediate structure. For comparative purpose, across-sectional view of an active matrix OLED 450 made in an embodimentaccording to FIG. 6 is shown in FIG. 7, which is analogous to FIG. 3J.In FIG. 7, reference numbers 201, 202, 203, 210, 220, and 230 are asdescribed above for FIG. 3. In this embodiment, the first, second andthird organic EL medium layers, 440, 442, and 444 include only layersother than an EIL. An optional common EIL layer 446 is provided over theorganic medium layers and a common cathode 448 is provided over thecommon EIL layer. Although not shown, the substrate may have includedcommon HIL and HTL layers as described previously. Prior to depositingthe common top electrode, or alternatively, a common organic EL layer ifthat is included, the top surface of the patterned organic EL mediumlayers may be treated to improve contact with the common top electrodeor common organic EL layer. This can help overcome contact resistanceintroduced by inadvertent layer damage or thin polymer residue that maybe present on the organic EL medium surfaces. For example, the topsurface of the organic EL medium layers may be treated with a low workfunction metal, e.g., an alkali metal, an alkaline metal or an alkalineearth metal. Typically, the low work function metal has a thickness ofless 2 nm or less, alternatively 1 nm or less, or even 0.5 nm or less.Alternatively, treatment may include a reducing gas environment, e.g. agas environment including hydrogen. Alternatively, treatment may includea substantially non-oxidizing plasma, e.g. one including hydrogen andanother non-oxidizing gas such as nitrogen or helium. Alternatively,treatment may include contact with a cleaning agent having a chemicalcomposition different from the lift-off agent, the cleaning agentincluding a fluorinated solvent. For example, the cleaning agent mayinclude a fluorinated solvent and a protic solvent such as an alcohol(e.g. IPA) at 15% or less by volume, alternatively 5% or less by volume.Alternatively, the protic solvent may include an organic acid at 5% orless by weight or alternatively 1% or less by weight. Alternatively, thecleaning agent may include a mixture of two fluorinated solvents, e.g.,a mixture of a fluorinated solvent used in the lift-off agent and asecond fluorinated solvent that is more polar or has less fluorinecontent by weight or both.

Referring again to FIGS. 2 and 3, in another embodiment, the topelectrodes 217, 227 and 237 are provided in a manner so that they covera slightly larger area than the organic EL medium layers. This can bedone by reducing the collimation of the top electrode deposition e.g.,by moving the top electrode source closer to the substrate as shown inFIG. 8. This allows the top electrode material to extend beyond theedges of the OLED and help seal the exposed edges to protect from waterand oxygen penetration. In FIG. 8, top electrode source 480 ispositioned so that top electrode material 482 emitted from the source isnot highly collimated and deposits a first top electrode 217 that, inthis embodiment, includes top electrode portion 217 a that extends overthe sides of organic EL medium layers 216. All other reference numbersin FIG. 8 are as described previously with respect to FIG. 3. A topelectrode material should be of a material and thickness so that it isrelatively inert itself to water and oxygen penetration, or able to forma non-harmful, inert oxide barrier layer. For example, the top electrodemay comprise aluminum or metal oxide that is at least 50 nm, preferablyat least 100 nm thick. The top electrode in this embodiment may be acathode or anode. In this embodiment, the organic EL medium layersshould be deposited in an area at least as large as the bottomelectrode, preferably larger, and it is preferred that the substrateinclude a bottom electrode-defining dielectric. This will preventshorting of the two electrodes.

In a manner similar to FIG. 8, but with respect to FIGS. 6 and 7, ratherthan a top electrode having a larger area, the top layer of the organicEL media layers can be provided to cover the edges of underlying organicEL media layers. In a non-limiting example, the top organic EL medialayer of an individual stack is a hole-blocking layer that is providedin an area slightly larger than the underlying layers, e.g., to protectedges of the LEL or other layers which may be more water or oxygensensitive than the HBL. This can also be done by selecting conditionsfor top organic EL media layer deposition that are less collimated thanunderlying layers.

Referring again to FIGS. 2 and 3, in an embodiment the OLED arrays eachhave an inverted structure wherein the cathode is the bottom electrodeand the anode is the top electrode. The top anode may further beprovided to cover the edges of the organic EL medium as described inFIG. 8. With the inverted structure, the sensitive EIL and cathode/EILare at the bottom and further away from the lift-off structure, itsassociated chemistry and potential adventitious water and oxygen therebyproviding a more robust structure.

Referring again to FIGS. 2 and 3, in an embodiment, a fluorinatedmaterial layer is vapor deposited after deposition of the first orsecond top electrodes or both, i.e., after step 107, but before step109, or after step 117, but before step 119. In this embodiment, theorganic EL medium and top electrodes are deposited in a reduced pressure(vacuum) environment as discussed previously. The vapor depositedfluorinated material layer can serve as a temporary barrier to water, oras a buffer layer against physical damage from handling, when thesubstrate is transferred to more ambient pressure conditions forlift-off processing. An example structure is shown in cross sectionalview in FIG. 9 which is identical to FIG. 3C with the exception of theadditional vapor deposited fluorinated material layer 490 and 490′. Inan embodiment, the fluorinated material layer is chosen to dissolve inthe lift-off solvent. In an alternative embodiment, the fluorinatedmaterial layer is selected so that it does not dissolve in the lift offsolvent, but rather, remains over the active OLED device and is liftedoff in the photoresist portions along with the unnecessary OLED and topelectrode materials as described earlier. Prior to deposition of thecommon top electrode, however, the fluorinated material layer should beremoved in an orthogonal solvent other than the lift-off solvent fromsteps 109 and 119. For example, the lift off solvent may be a firsthydrofluoroether and the fluorinated material layer removal step may usea different hydrofluoroether or a perfluorinated solvent, or rice versaand the lift-off solvent is a perfluorinated solvent.

In a similar embodiment and referring to FIGS. 6 and 7, vapor depositedfluorinated material layer may be provided after deposition of theorganic EL medium layers, e.g., after step 405 but before step 409. Asbefore, the fluorinated material layer may be chosen to dissolve in thelift-off solvent, or alternatively, the fluorinated material layer isselected so that it does not dissolve in the lift off solvent. If thelatter, prior to deposition of the common top electrode and any commonorganic layers, the fluorinated material layer should be removed in anorthogonal solvent other than the lift-off solvent from steps 109 and119.

Referring again to FIGS. 2 and 3, one or more of the lift-off structureshas a multi-layer structure, e.g., the two-layer structure shown in FIG.3 and further illustrated in FIG. 5. In an embodiment, the lift-offstructure is removed by using lift-off agent comprising a fluorinatedsolvent having a density greater than the effective density of thephotoresist layer plus overlying organic EL medium layers and thecathode. In this context, “effective density” is the total mass of thephotoresist layer plus any overlying layers divided by the volume ofsuch photoresist layer and overlying layers. This simplifies removal ofthe photoresist layer (plus overlying layers) and encourages separationof such layers by enabling these layers to quickly rise to the topsurface of a lift-off agent liquid. This can speed lift-off and alsoreduce the chance that possible debris from the lift-off materials willdamage the remaining OLED structure. By concentrating such debris nearthe surface of the lift-off agent liquid, a processing machine can bedesigned to readily filter out the debris.

Referring again to FIGS. 2 and 3, in an embodiment, the photoresist orcathode is selected to have some residual stress that encourages thelift-off portion to curl during lift off. This curling action can morequickly expose fresh base layer thereby speeding up the lift-off step.In an embodiment, the curl force induces an arc of at least 180° in atleast a portion of the lift-off structure. In an embodiment, the curlforce induces an arc of at least 360° in at least a portion of thelift-off structure, i.e., at least a portion of the lift-off structurerolls up on itself.

Referring again to FIGS. 2 and 3, in an embodiment, the cathode isselected to have some magnetic properties so that a magnet in a lift-offagent bath can attract the removed portion. This can speed up lift offand also reduce the chance that possible debris from the lift-offmaterials will damage the remaining OLED structure.

Referring to FIGS. 3J and 3K, it is possible that the common topelectrode deposition might not go as drawn. If the common top electrodeis thinner than the organic EL thickness, there is chance for adiscontinuity as shown in FIG. 10A, which is otherwise the same as FIG.3K except that the thin common top electrode 241 does not readilyconnect the other top electrodes. This may produce a defective activematrix OLED device, 251. Further, even as drawn in FIG. 3K, there is achance for shorting between the top and bottom electrodes. In anembodiment, a patterned dielectric layer is provided after forming thethird intermediate structure to aid the deposition of the common topelectrode. Such patterned dielectric may be provided from a fluorinatedphotopolymer from a fluorinated solvent, e.g., a cross-linkingfluorinated polymer as described in International Application Nos.PCT/US2014/047800 and PCT/US2015/014425, exposing and developing in anorthogonal developing agent. As shown in FIG. 10B, the patterned(optionally fluorinated) dielectric 495 is provided over thirdintermediate structure 238 that is otherwise the same as that shown inFIG. 3J. The patterned dielectric 495 has a relatively gentle slope toensure good contact between the top electrodes of each OLED array andthe common top electrode 242, even if the common top electrode isthinner than the organic EL medium thickness. Further, there is nowconsiderable separation between the top electrode and bottom electrodes,reducing the chance for shorts. The array of patterned openings in thedielectric (sometimes referred to as a “pixel definition layer” or PDL)generally defines the display region of a display device.

Referring again to FIGS. 2 and 3, in an embodiment, the lift-offstructures employ a negative type photoresist and the top electrodes aresubstantially opaque to patterning radiation. In this way, underlyingorganic EL media layers are protected from potentially harmful radiationsuch as UV light.

In the embodiments described in FIGS. 2 and 6, three lift-off structuresare fabricated to pattern three different colors. In an alternativeembodiment, only two lift-off structures are used as described in FIGS.11 and 12A-12J.

In step 501, third organic EL medium layers (e.g. for a red-emittingOLED) are deposited over an OLED substrate having first, second andthird arrays of bottom electrodes. The third organic EL medium layerswill eventually be used to form an OLED over the third array of bottomelectrode. This is shown in cross-sectional view in FIG. 12A wherein anOLED substrate (having first, second and third arrays of bottomelectrodes) is provided as described previously in FIG. 3A and the thirdorganic EL medium layers 636 are commonly deposited over all of thearrays of electrodes. A top electrode is not provided at this time. Inan embodiment, the third organic EL medium is easily dry-etched and doesnot include substantial amounts of metal-containing materials in itsLEL, optional HBL or optional ETL, e.g., aluminum quinolate complexes orphosphorescent iridium dopants.

In step 503, over the third organic EL medium layers a first lift-offstructure is formed having an array of openings corresponding to a firstarray of bottom electrodes. FIG. 12B shows a first lift-off structure611 having an opening 615 corresponding to a first bottom electrode. Inthe embodiment shown here, the first lift-off structure 611 is a bilayerof first material layer 612 and first patterned photoresist layer 613.An undercut region 614 is formed in layer 612. The first lift-offstructure 611 may instead be a single layer or have more than twolayers.

In step 505 the first-lift off structure is used as an etch mask foretching the third organic EL medium layers. These layers are etched in apattern corresponding to the first array of bottom electrodes. As shownin FIG. 12C, the removed portion 636′ of the third organic EL mediumlayers exposes the first array of bottom electrodes for subsequent OLEDdeposition steps as described below. Methods of etching include thosementioned above with respect to dry-etching. In an embodiment, theelectrode-separating dielectric 203 (see FIG. 3A) is more etch resistantthan the organic EL medium layers.

In step 507, first organic EL medium layers (e.g., for a green-emittingOLED) are deposited. As shown in FIG. 12D, a portion of the firstorganic EL medium layers 616′ is deposited over the lift-off structurewhereas another portion of the first organic EL medium layers 616 goesthrough the opening 615 and is deposited on the first array of bottomelectrodes. Although not shown in the present embodiment, a first topelectrode may optionally be deposited over the first organic EL mediumlayers in a manner similar to that shown in FIG. 3C.

In step 509, the first lift-off structure is removed to form a firstintermediate structure 618 as shown in FIG. 12E. In step 511, a secondlift-off structure 621 having an array of openings 625 corresponding tothe second array of bottom electrodes is formed over the firstintermediate structure. In the embodiment shown here in FIG. 12F, thesecond lift-off structure 621 is a bilayer of second material layer 622and second patterned photoresist layer 623. An undercut region 624 isformed in layer 622. The second lift-off structure 621 may instead be asingle layer or have more than two layers.

In step 513 the second-lift off structure is used as an etch mask foretching the first organic EL medium layers. These layers are etched in apattern corresponding to the second array of bottom electrodes. As shownin FIG. 12G, the removed portion 636″ of the first organic EL mediumlayers exposes the first array of bottom electrodes for subsequent OLEDdeposition steps as described below. Methods of etching include thosementioned above with respect to dry-etching. In an embodiment, theelectrode-separating dielectric 203 (see FIG. 3A) is more etch resistantthan the organic EL medium layers.

In step 515, second organic EL medium layers (e.g., for a blue-emittingOLED) are deposited. As shown in FIG. 12H, a portion of the secondorganic EL medium layers 626′ is deposited over the lift-off structurewhereas another portion of second third organic EL medium layers 626goes through the opening 625 and is deposited on the second array ofbottom electrodes. Although not shown in the present embodiment, asecond top electrode may optionally be deposited over the second organicEL medium layers in a manner similar to that shown in FIG. 3C.

In step 517, the second lift-offstructure is removed to form a secondintermediate structure 628 as shown in FIG. 12I. In steps 519, one ormore common organic EL medium layers 646 are optionally provided overthe second intermediate structure and in step 521 a common electrode 648is provided thereby forming active matrix OLED device 650. FIG. 12Jshows the embodiment with the optional common organic EL medium layer(s)646. When a common organic EL medium is intended for deposition, firstand second top electrodes should not be deposited over the first andsecond organic EL medium layers. The top surfaces of patterned organicEL medium layers may optionally be cleaned or treated as previouslydescribed with respect to FIGS. 6 and 7.

Referring to FIGS. 11 and 12, in an embodiment, each OLED stack isprovided up through at least its respective LEL, but does not include anEIL or any layers having electron rich dopants such as alkali metal,alkaline metal or alkaline earth metal dopants. For example, the OLEDstack may be provided up to and including a hole-blocking layer. Itshould also be noted that third organic EL medium layers may be providedin interstitial areas between the first and second organic EL mediumlayers. This can be advantageous for providing a uniform surface for thedeposition of subsequent common layers. It also may help prevent shortsin the event that a device has a defect (e.g. in the PDL or in thepatterning of other colors) that exposes an unintended area of a bottomelectrode. The third organic EL medium layers would cover such defect,and although it may slightly reduce the color purity of a defectivepixel if it was intended to emit colors from the first or second organicEL medium layers, it would more importantly light up upon application ofan appropriate voltage rather than producing a dark spot.

Referring again to FIGS. 11 and 12, in an embodiment, one or more of thethird organic EL medium layers are coated from solution. In anembodiment, one or more of the third and first organic EL medium layersare coated from solution. In an embodiment, the third organic EL mediumincludes a light-emitting layer deposited from solution (e.g., apolymeric LEL) whereas the first organic EL medium or second organic ELmedium or both includes an LEL provided by vapor deposition.

Those skilled in the art will recognize that many of the embodimentsdescribed above with respect to FIGS. 2, 3, 6 and 7 can be applied in asimilar fashion with respect to the embodiments of FIGS. 11 and 12. Anadvantage of the embodiments shown in FIGS. 11 and 12 is that only twolift-off steps are required for a three-color OLED.

FIGS. 13A through 13D shows a series of cross-sectional views in anotherembodiment of forming an organic device. In FIG. 13A, a device substrate700 is provided, which may optionally be flexible and may optionallyinclude a support layer (e.g. as described above for OLEDs) in additionto other layers and features necessary to provide a desired organicdevice. For example, the organic device may be an OLED, a display, alighting device, a chemical sensor, a touch sensor, a photovoltaic, aTFT backplane, or a bioelectronic or medical device.

Over the device substrate 700 is provided a first undercut lift-offstructure 711 having a first opening 715 and forms an area of uncovereddevice substrate 703. The lift-off structure may include any of thosepreviously discussed so long as there is an undercut. In the embodimentof FIG. 13A, the first undercut lift-off structure 711 is a single layerhaving undercut region 714, e.g., a patterned fluorinated photoresistdeveloped using a fluorinated solvent. Alternatively, the undercutlift-off structure could instead comprise two or more patterned layers,e.g., including a fluorinated material base layer and an overlyingphotoresist layer wherein the fluorinated material base layer isundercut relative to the photoresist layer.

As shown in FIG. 13B, a first active organic material layer is thendeposited over the first undercut lift-off structure and over a firstportion 705 of the area of uncovered device substrate. The activeorganic material deposited over the lift-off structure is shown as 713′and the active organic material deposited over the first portion isshown as 713. In an embodiment, the first active organic material layeris vapor-deposited in a reduced-pressure environment with a reasonableamount of collimation so that the material is deposited in an areasimilar in size to opening 715. Alternatively, rather than depositingthe first active organic material directly, a growth catalyst, anadhesion promoter or a linking group is provided over the first portion705 by a collimated means and the first active organic material layer isselectively deposited from solution or other non-collimated vapor phasein the areas occupied by the growth catalyst, adhesion promoter orlinking group. The first active organic material layer may include, forexample, an organic conductor, an organic semiconductor, a chargetransport material, a light-emitting material, or a biological material.In an embodiment, the first active organic material layer is sensitiveto water or oxygen or both.

Referring to FIG. 13C, a second material layer is deposited over thefirst active organic material layer and over a second portion 707 of thearea of uncovered substrate. The second material layer deposited overthe lift-off structure is shown as 717′ and the second material layerdeposited over the second portion is shown as 717. The second portionarea is larger than the first portion area and so the second materiallayer 717 extends beyond and covers the sidewalls of the first activeorganic material layer 713 in the first portion. The second materiallayer may be deposited from solution or by vapor deposition so long asthe vapor is not so highly collimated that it limits the second portionarea to the degree that it prevents or limits coverage of the secondmaterial layer over the sidewalls of the first active organic materiallayer. Alternatively, rather than depositing the second material layerdirectly, a growth catalyst, an adhesion promoter or a linking group isprovided over regions other than the sidewalls of the lift-offstructure, and the second material layer is then selectively depositedfrom solution or other vapor phase in the areas occupied by the growthcatalyst, adhesion promoter or linking group.

In an embodiment, the second material layer is electrically conductive.For example, the second material layer may include an organic conductor,a metal, a metal oxide, graphene or graphene-oxide. In an embodiment,the second material layer comprises a second active organic materialdifferent from the first active organic material layer. For example,this second active organic material may include an upper layer in anorganic EL media stack such as a charge transport material or lightemitting material, or it may include a biological material or an organicsemiconductor. In an embodiment, the second material layer is laterremoved and does not form part of the organic device in its final form.For example, the second material layer may include a fluorinatedmaterial. In an embodiment, the second material layer is less sensitiveto water or oxygen, or both, than the first active organic materiallayer. In an embodiment, the second material layer at least partiallyprotects the first active organic material layer from water or oxygen orboth, for example, by slowing the ingress of water or oxygen.

As shown in FIG. 13D, the first undercut lift-off structure is removed,e.g., by methods described previously, thereby forming an intermediatestructure or organic device 720 having a patterned first active organicmaterial layer and a patterned second material layer over the substrate.The first opening may optionally be part of a first array of openingshaving a first pattern. Further, the substrate may optionally include afirst array of bottom electrodes in alignment with the first openings.

As described, a lift-off structure may include a fluorinated materialbase layer and a photoresist wherein the fluorinated material base layeracts as a lift-off layer. In an embodiment, the lift-off agent comprisesa fluorinated solvent, e.g., a perfluorinated solvent or ahydrofluoroether, and a film-forming, lift-off fluorinated material thatmay be the same as or different from the fluorinated material used inthe fluorinated material base layer. For example, an intermediate devicestructure may be formed from the lift-off step and the intermediatestructure is intended for further processing. By including a lift-offfluorinated material in the lift-off solvent, a protective layer of thelift-off fluorinated material is formed upon evaporation or drying. Thiscan protect underlying sensitive structures from adventitiouscontaminants and physical damage that may occur during storage ortransfer to other processing stations.

In an embodiment, the lift-off fluorinated material is the same as thefluorinated material of the fluorinated material base layer and at leasta portion of the lift-off fluorinated material in the lift-off agent isa seasoning byproduct of the lift-off step that is deliberately allowedto build up. In other words, rather than removing dissolved fluorinatedmaterial from a lift-off processing tank or providing multiple washes toremove residual fluorinated material, a layer of such lift-offfluorinated material is deliberately allowed to form on a patterneddevice structure surface. In an embodiment, the dried lift-offfluorinated material has a thickness in a range of 10 nm to 1000 nmthick, alternatively 50 nm to 500 nm. In an embodiment, the layer oflift-off fluorinated material is thick enough to be used as a subsequentbase layer in the fabrication of another lift-off structure for furtherpatterning. In an embodiment, the layer of lift-off fluorinated materialis largely dissolved into a subsequent fluorinated material base layercoating and becomes part of the new fluorinated material base layer.

For example, shown in FIG. 14A is a structure identical to thatdescribed for FIG. 3F, and in particular, the second material layer 222is a fluorinated material. When contacted with a lift-off agentcomprising a lift-off fluorinated material, rather than forming theintermediate structure 228 of FIG. 3G, the intermediate structure 228Aof FIG. 14B is formed having a lift-off fluorinated material layer 222A.In an embodiment, this may be used to form a base layer, or a portion ofa base layer, in another lift-off structure.

The lift-off fluorinated material can be added to a lift-off processreplenishment supply. Alternatively, the lift-off fluorinated materialcan be provided by seasoning a lift-off processing tank that allowsbuild-up of a fluorinated material from the lift-off structure,preferably in conjunction with a replenishment system and arecirculation system for filtering insoluble lift-off portions. Inaddition to adding protection, it can save money by reducing the volumeof fresh lift-off agent consumed. When all the patterning steps aredone, however, the intermediate structure should be cleaned with freshlift-off agent or treated in ways previously described to remove residueprior to deposition of any common organic EL layers or a common topelectrode.

Some non-limiting embodiments of the present disclosure are definedbelow.

1. A method of making an OLED device comprising:

a) providing a device substrate having a first array of bottomelectrodes and a second array of bottom electrodes;

b) providing a first undercut lift-off structure over the devicesubstrate having a first pattern of openings corresponding to the firstarray of bottom electrodes;

c) depositing one or more first organic EL medium layers, including atleast a first light-emitting layer, and a first top electrode layer overthe first undercut lift-off structure and over the first array of bottomelectrodes;

d) removing the first undercut lift-offstructure and overlying firstorganic EL medium layer(s) and first top electrode to form a firstintermediate structure;

e) providing a second undercut lift-off structure over the firstintermediate structure having a second pattern of openings correspondingto the second array of bottom electrodes;

f) depositing one or more second organic EL medium layers, including atleast a second light-emitting layer, and a second top electrode over thesecond undercut lift-off structure and over the second array of bottomelectrodes;

g) removing the second undercut lift-off structure and overlying secondorganic EL medium layer(s) and second top electrode to form a secondintermediate structure; and

h) providing a common top electrode to electrically connect the firstand second top electrode layers.

2. The method of embodiment 1 wherein at least one lift-off structureincludes at least two patterned layers including a fluorinated materialbase layer and an overlying photoresist layer, wherein the fluorinatedmaterial base layer is undercut relative to the photoresist layer.

3. The method of embodiment 1 wherein at least one lift-off structureincludes a patterned fluorinated photoresist developed using afluorinated solvent and having an undercut profile.

4. The method according to any of embodiments 1-3 further including adry-etch cleaning step between steps (b) and (c) or between steps (e)and (f) or both.

5. The method according to any of embodiments 1-4 wherein at least onelift-off structure absorbs or blocks underlying layers from at least 80%of imaging radiation used in the formation of the lift-off structure.

6. The method according to any of embodiments 1-5 wherein at least onelift-off structure comprises a negative tone photosensitive film thatabsorbs or blocks at least 80% of imaging radiation and wherein thefirst or second top electrodes or both absorb or block at least 80% ofany imaging radiation that passes through an overlying lift-offstructure.

7. The method according to any of embodiments 1-6 wherein the effectivedensity of at least one lift-off structure with its correspondingoverlying organic EL medium layers and overlying top electrode layer isless than the density of a lift-off agent used to remove the lift-offstructure.

8. The method according to embodiment 7 wherein the lift-off agentcomprises a fluorinated solvent.

9. The method according to any of embodiments 1-8 wherein the bottomelectrodes act as cathodes and the top electrodes act as anodes.

10. The method according to any of embodiments 1-9 wherein at least onetop electrode is deposited so that it covers the sidewalls of underlyingorganic EL medium layers.

11. The method according any of embodiments 1-10 further including vapordepositing a fluorinated material over a top electrode between steps (c)and (d), or between steps (f) and (g), or both.

12. The method according to any of embodiments 1-11 wherein one or morelift-off structures curls during its removal in a lift-off agent.

13. The method according to any of embodiments 1-12 further comprising,prior to step (h), providing a third undercut lift-offstructure over thesecond intermediate structure having a third pattern of openingscorresponding to a third array of bottom electrodes;

depositing one or more third organic EL medium layers, including atleast a third light-emitting layer, and a third top electrode over thethird undercut lift-off structure and over the third array of bottomelectrodes:

removing the third undercut lift-off structure and overlying thirdorganic EL medium layer(s) and third top electrode to form a thirdintermediate structure.

14. The method according to any of embodiments 1-13 further comprising,prior to step (h), cleaning the surface of the top electrodes ofresidual fluorinated material.

15. The method according to embodiment 14 wherein the cleaning comprisescontact with a cleaning agent having a chemical composition differentfrom the lift-off agent, the cleaning agent comprising a fluorinatedsolvent.

16. The method according to embodiment 14 or 15 wherein the cleaningcomprises dry etching.

17. The method according to embodiment 16 wherein the dry etchingincludes an argon plasma, oxygen plasma or a substantially non-oxidizingplasma.

18. The method according to any of embodiments 1-17 wherein at least onelift-off structure includes at least two patterned layers including afluorinated material base layer and an overlying photoresist layer, theoverlying photoresist layer provided from a photoresist compositioncomprising a fluorinated coating solvent.

19. The method according to embodiment 18 wherein the photoresist layercomprises a fluorinated photoresist.

20. The method according to embodiment 18 or 19 wherein the fluorinatedmaterial base layer includes a cyclic perfluorinated polymer and thefluorinated coating solvent is a hydrofluoroether.

21. The method according to any of embodiments 1-20 further including,prior to step (h) treating the top electrodes with a low work-functionmetal, a reducing gas environment or a substantially non-oxidizingplasma.

22. A method of making an OLED device comprising:

a) providing a device substrate having a first array of bottomelectrodes and a second array of bottom electrodes;

b) providing a first undercut lift-off structure over the devicesubstrate having a first pattern of openings corresponding to the firstarray of bottom electrodes;

c) depositing one or more first organic EL medium layers including atleast a first light-emitting layer over the first undercut lift-offstructure and over the first array of bottom electrodes;

d) removing the first undercut lift-offstructure and overlying firstorganic EL medium layer(s) by treatment with a first lift-off agentcomprising a fluorinated solvent to form a first intermediate structure;

e) providing a second undercut lift-off structure over the firstintermediate structure having a second pattern of openings correspondingto the second array of bottom electrodes;

f) depositing one or more second organic EL medium layers including atleast a second light-emitting layer over the second undercut lift-offstructure and over the second array of bottom electrodes;

g) removing the second undercut lift-off structure and overlying secondorganic EL medium layer(s) by treatment with a second lift-off agentcomprising a fluorinated solvent to form a second intermediatestructure; and

h) providing a common top electrode in electrical contact with the firstand second organic EL medium layers.

23. The method of embodiment 22 wherein at least one lift-off structureincludes at least two patterned layers including a fluorinated materialbase layer and an overlying photoresist layer wherein the fluorinatedmaterial base layer is undercut relative to the photoresist layer.

24. The method of embodiment 22 wherein at least one lift-off structureincludes a patterned fluorinated photoresist developed using afluorinated solvent and having an undercut profile.

25. The method according to any of embodiments 22-25 further including adry-etch cleaning step between steps (b) and (c) or between steps (e)and (f) or both.

26. The method according to any of embodiments 22-25 wherein at leastone lift-off structure absorbs or blocks underlying layers from at least80% of imaging radiation used in the formation of the at least onelift-off structure.

27. The method according to any of embodiments 22-26 wherein theeffective density of at least one lift-off structure with itscorresponding overlying organic EL medium layers is less than thedensity of the corresponding liquid lift-off agent used to remove thelift-offstructure.

28. The method according to embodiment 27 wherein at least one lift-offagent comprises a hydrofluoroether.

29. The method according to any of embodiments 22-28 wherein the bottomelectrodes act as cathodes and the common top electrode acts as arespective anode.

30. The method according to any of embodiments 22-29 wherein at leastone top organic EL medium layer is deposited so that it covers thesidewalls of one or more underlying organic EL medium layers.

31. The method according any of embodiments 22-30 further includingvapor depositing a fluorinated material over the organic EL mediumlayers between steps (c) and (d), or between steps (f) and (g), or both.

32. The method according to any of embodiments 22-31 wherein one or morelift-off structures curls during its removal in the lift-off agent.

33. The method according to any of embodiments 22-32 further comprising,prior to step (h), providing a third undercut lift-off structure overthe second intermediate structure having a third pattern of openingscorresponding to a third array of bottom electrodes;

depositing third organic EL medium layers including at least a thirdlight-emitting layer over the third undercut lift-off structure and overthe third array of bottom electrodes;

removing the third undercut lift-off structure and overlying thirdorganic EL medium layer(s) by treatment with a third lift-off agentcomprising a fluorinated solvent to form a third intermediate structure:

34. The method according to any of embodiments 22-33 further comprisingdepositing a common organic EL layer prior to depositing the common topelectrode.

35. The method according to any of embodiments 22-34 further comprising,prior to depositing the common top electrode, or in the case ofembodiment 34, prior to depositing the common organic EL layer, cleaningthe intermediate structure of residual fluorinated material.

36. The method according to embodiment 35 wherein the cleaning comprisescontact with a cleaning agent having a chemical composition differentfrom the lift-off agent, the cleaning agent comprising a fluorinatedsolvent.

37. The method according to any of embodiments 22-36 wherein at leastone lift-off structure includes at least two patterned layers includinga fluorinated material base layer and an overlying photoresist layer,the overlying photoresist layer provided from a photoresist compositioncomprising a fluorinated coating solvent.

38. The embodiment according to embodiment 37 wherein the photoresistlayer comprises a fluorinated photoresist.

39. The embodiment according to embodiment 37 or 38 wherein thefluorinated material base layer includes a cyclic perfluorinated polymerand the fluorinated coating solvent is a hydrofluoroether.

40. The method according to any of embodiments 22-39 further includingtreating the top surface of patterned organic EL medium layers with alow work function metal or a substantially non-oxidizing plasma prior todeposition of the common top electrode, or alternatively, prior todeposition of a common organic EL layer if such layer is used.

41. A method of making an OLED device comprising:

a) providing a device substrate having a first array of bottomelectrodes and a second array of bottom electrodes;

b) depositing second organic EL medium layers over the device substrateincluding over the first and second arrays of bottom electrodes, whereinthe second organic EL medium layers include at least a secondlight-emitting layer;

c) providing over the second organic EL medium layers a first undercutlift-off structure having a first pattern of openings corresponding tothe first array of bottom electrodes;

d) using the first undercut lift-offstructure as an etch mask andremoving common organic EL medium layers from areas over the first arrayof bottom electrodes;

e) depositing first organic EL medium layers including at least a firstlight-emitting layer over the first undercut lift-off structure and overthe first array of bottom electrodes;

f) removing the first undercut lift-off structure and overlying firstorganic EL medium layers to form a first intermediate structure; and

g) providing a common top electrode in electrical contact with the firstand second organic EL medium layers.

42. The method of embodiment 41 wherein at the first undercut lift-offstructure includes at least two patterned layers including a fluorinatedmaterial base layer and an overlying photoresist layer wherein thefluorinated material base layer is undercut relative to the photoresistlayer.

43. The method of embodiment 41 wherein the first undercut lift-offstructure includes a patterned fluorinated photoresist developed using afluorinated solvent and having an undercut profile.

44. The method according to any of embodiments 41-43 wherein the firstundercut lift-off structure absorbs or blocks underlying layers from atleast 80% of imaging radiation used in the formation of the lift-offstructure.

45. The method according to any of embodiments 41-44 wherein theeffective density of the first undercut lift-off structure with itscorresponding overlying organic EL medium layers is less than thedensity of a lift-off agent used to remove the lift-off structure.

46. The method according to embodiment 45 wherein the lift-off agentcomprises a fluorinated solvent.

47. The method according to any of embodiments 41-46 wherein the bottomelectrodes act as cathodes and the common top electrode acts as arespective anode.

48. The method according to any of embodiments 41-47 wherein at leastone top organic EL medium layer is deposited so that it covers thesidewalls of underlying organic EL medium layers.

49. The method according any of embodiments 41-48 further includingvapor depositing a fluorinated material over the organic EL mediumlayers between steps (e) and (f).

50. The method according to any of embodiments 41-49 wherein the firstundercut lift-off structures curls during its removal in a lift-offagent.

51. The method according to any of embodiments 41-50 further comprisingdepositing one or more common organic EL medium layers prior todepositing the common top electrode.

52. The method according to any of embodiments 41-51 further comprising,prior to depositing the common top electrode, or in the case ofembodiment 51, prior to depositing the common organic EL layer, cleaningthe intermediate structure of residual fluorinated material.

53. The method according to embodiment 52 wherein the cleaning comprisescontact with a cleaning agent having a chemical composition differentfrom the lift-off agent, the cleaning agent comprising a fluorinatedsolvent.

54. The method according to any of embodiments 41-53 wherein the firstundercut lift-off structure includes at least two patterned layersincluding a fluorinated material base layer and an overlying photoresistlayer, the overlying photoresist layer provided from a photoresistcomposition comprising a fluorinated coating solvent.

55. The method according to embodiment 54 wherein the photoresist layercomprises a fluorinated photoresist.

56. The method according to embodiment 54 or 55 wherein the fluorinatedmaterial base layer includes a cyclic perfluorinated polymer and thefluorinated coating solvent is a hydrofluoroether.

57. The method according to any of embodiments 41-56 further includingtreating the top surface of patterned organic EL medium layers with alow work function metal or a substantially non-oxidizing plasma prior todeposition of the common top electrode, or alternatively, prior todeposition of a common organic EL layer if such layer is used.

58. A method of making an organic device comprising:

a) over a device substrate, providing a first undercut lift-offstructure having a first opening that forms an area of uncovered devicesubstrate;

b) depositing a first active organic material layer over the firstundercut lift-off structure and over a first portion of the area ofuncovered device substrate;

c) depositing a second material layer over the first active organicmaterial layer and over a second portion of the area of uncoveredsubstrate thereby covering edge portions of the first active organicmaterial layer; and

d) removing the first lift-off structure and overlying layers.

59. The method of embodiment 58 wherein the first active organicmaterial layer includes an organic conductor, an organic semiconductor,a charge transport material, a light-emitting material, or a biologicalmaterial.

60. The method of embodiment 59 wherein the first active organicmaterial layer is vapor deposited in a reduced-pressure environment.

61. The method according to any of embodiments 58-60 wherein the secondmaterial layer is electrically conductive.

62. The method according to embodiment 61 wherein the second materiallayer comprises an organic conductor, a metal, a metal oxide, grapheneor graphene-oxide.

63. The method according to any of embodiments 58-60 wherein the secondmaterial layer comprises a second active organic material.

64. The method of embodiment 63 wherein the second material layerincludes an organic semiconductor, a charge transport material, alight-emitting material or a biological material.

65. The method according to any of embodiments 58-60 wherein the secondmaterial layer is later removed and does not form part of the organicdevice in its final form.

66. The method according to embodiment 65 wherein the second materiallayer includes a fluorinated material.

67. The method according to any of embodiments 58-66 wherein the secondmaterial layer is less sensitive to water or oxygen, or both, than thefirst active organic material layer.

68. The method according to any of embodiments 58-67 wherein the secondmaterial layer at least partially protects the first active organicmaterial layer from water or oxygen or both.

69. The method according to any of embodiments 58-68 wherein theuncovered substrate comprises a bottom electrode in alignment with thefirst opening and the first active organic material layer completelycovers the bottom electrode.

70. The method according to any of embodiments 58-69 wherein the firstundercut lift-off structure includes at least two patterned layersincluding a fluorinated material base layer and an overlying photoresistlayer wherein the fluorinated material base layer is undercut relativeto the photoresist layer.

71. The method according to any of embodiments 58-69 wherein the firstundercut lift-off structure includes a patterned fluorinated photoresistdeveloped using a fluorinated solvent.

72. The method according to any of embodiments 58-71 wherein the organicdevice is an OLED, a display, a lighting device, a chemical sensor, atouch sensor, a photovoltaic, a TFT backplane, or a bioelectronic ormedical device.

73. The method according to any of embodiments 58-72 wherein the devicesubstrate is flexible.

74. The method according to any of embodiments 58-73 wherein the firstopening is part of a first array of openings having a first pattern.

75. A method of patterning a device comprising:

a) providing a device substrate;

b) providing over the device substrate a fluorinated material layercomprising a first fluorinated material and providing a photoresistlayer over the fluorinated material layer;

c) exposing and developing the photoresist layer to form a patternedphotoresist;

d) transferring the photoresist pattern to the fluorinated materiallayer, thereby forming a first pattern of uncovered substrate;

e) depositing one or more material layers over the patterned photoresistand at least a portion of the uncovered substrate to form a firstintermediate structure; and

f) contacting the first intermediate structure with a lift-off agentthat dissolves the fluorinated material layer, thereby causingseparation the patterned photoresist and overlying one or more layers,wherein the lift-off agent includes a fluorinated solvent and afilm-forming second fluorinated material that may be the same as ordifferent from the first fluorinated material.

76. The method according to embodiment 75 wherein the second fluorinatedmaterial forms a layer that covers the substrate including the one ormore material layers deposited over the portion of uncovered substrate.

77. The method according to embodiments 76 further comprising providinga second photoresist over the layer of second fluorinated material.

78. The method according to any of embodiments 75-77 wherein the firstand second fluorinated materials are substantially the same.

79. The method according to any of embodiments 75-78 wherein thefluorinated solvent is a hydrofluoroether.

80. A method of patterning an organic device comprising:

a) providing a device substrate;

b) providing over the device substrate a fluorinated material layercomprising a first fluorinated material and providing a photoresistlayer over the fluorinated material layer;

c) exposing and developing the photoresist layer to form a patternedphotoresist;

d) transferring the photoresist pattern to the fluorinated materiallayer, thereby forming a first pattern of uncovered substrate and apatterned fluorinated material layer having an undercut structurerelative to the photoresist layer;

e) depositing one or more material layers over the patterned photoresistand at least a portion of the uncovered substrate to form a firstintermediate structure; and

f) contacting the first intermediate structure with a lift-off agentthat dissolves the fluorinated material layer, thereby causingseparation the patterned photoresist and overlying one or more materiallayers, wherein the lift-off agent comprises a fluorinated solvent andthe effective density of the patterned photoresist with itscorresponding overlying material layers is less than the density of thelift-off agent.

81. The method of embodiment 80 wherein the patterned photoresist andoverlying one or more material layers are selected to at least partiallyroll up and float away from the device substrate during step (f).

82. A method of making a device comprising:

a) over a device substrate, providing a first undercut lift-offstructure having a first opening that forms an area of uncovered devicesubstrate;

b) vapor depositing a first material layer over the first undercutlift-off structure and over a first portion of the area of uncovereddevice substrate;

c) vapor depositing a fluorinated material layer over the first materiallayer and optionally over a second portion of the area of uncoveredsubstrate thereby optionally covering edge portions of the firstmaterial layer; and

d) removing the first lift-off structure and overlying layers by contactwith a lift-off agent comprising a first fluorinated solvent that doesnot dissolve the vapor deposited fluorinated material layer therebyforming a first protected patterned structure having a patterned firstmaterial layer and an overlying patterned fluorinated material layer.

83. The method of embodiment 82 wherein the first protected patternedstructure is subjected to one or more further patterning steps followedby removal of the patterned fluorinated material layer by contact with aremoving agent comprising a second fluorinated solvent capable ofdissolving the fluorinated material.

84. A full color OLED display comprising:

a substrate having a display region, the display region including anarray of first, second and third organic EL elements, each array havingindividually patterned light-emitting layers for emission of differentlycolored light,

wherein each of the first organic EL elements is spaced 4 μm or lessfrom a second or third organic EL element and a combined emissive areaof all of the first, second and third organic EL elements is at least60% of a total area occupied by the display region.

85. The OLED display of embodiment 84 wherein the substrate includes anactive matrix backplane having an array of first, second and thirdbottom electrodes and a pixel definition layer formed in registrationwith the bottom electrodes.

86. The OLED display according to embodiment 84 or 85 further comprisingan electron transporting layer that is commonly deposited over theseparately patterned light-emitting layers, wherein the electrontransporting layer contacts a different underlying patterned OLEDmaterial in each of the first, second and third arrays.

87. The OLED display according to any of embodiments 84-86 whereinmaterial corresponding to the patterned light-emitting layer of thethird organic EL element is also formed in interstitial non-emissiveareas between the second and third organic EL elements.

88. A full color OLED display comprising:

a substrate having a display region, the display region including anarray of first, second and third organic EL elements, each array havingindividually patterned light-emitting layers for emission of differentlycolored light,

wherein the display region has an aperture ratio of greater than about60% and a resolution of greater than about 600 ppi.

89. The OLED display of embodiment 88, wherein the aperture ratio isgreater than about 70%.

90. The OLED display of embodiment 88 or 89, wherein the display regionhas a resolution of greater than about 700 ppi.

91. The OLED display according to any of embodiments 88-90, wherein thedisplay region has a resolution of greater than about 800 ppi.

92. The OLED display according to any of embodiments 88-91 wherein eachof the first, second and third organic elements are less than about 25microns in size in any dimension.

93. The OLED display according to any of embodiments 88-92 wherein eachof the first, second and third organic elements are less than about 15microns in size in any dimension.

94. The OLED display according to any of embodiments 88-93 wherein eachof the first, second and third organic elements are less than about 15microns in size in any dimension.

95. The OLED display according to any of embodiments 88-94 wherein eachof the first, second and third organic elements are less than about 5microns in size in any dimension.

96. The OLED display according to any of embodiments 88-95, wherein thefirst, second and third organic EL elements emit red, green, and bluelight, respectively.

97. The OLED display according to any of embodiments 88-96, wherein thecombined emissive area of a first, second, and third organic EL elementis less than about 1100 square microns.

98. The OLED display according to any of embodiments 88-97, wherein thecombined emissive area of a first, second, and third organic EL elementis less than about 500 square microns.

99. A full color OLED display comprising:

a substrate having a display region, the display region including anarray of first, second and third sub-pixels, each array havingindividually patterned light-emitting layers for emission of differentlycolored light,

wherein each of the first, second and third sub-pixels has a size ofless than about 25 microns in any dimension and the display region hasan aperture ratio of greater than about 60%.

100. The OLED display of embodiment 99, wherein the display region has aresolution of greater than about 600 ppi.

101. The OLED display of embodiment 99 or 100, wherein each of thefirst, second and third sub-pixels has a size of less than about 20microns in any dimension.

102. The OLED display according to any of embodiments 99-101, whereineach of the first, second and third sub-pixels has a size of less thanabout 15 microns in any dimension.

103. The OLED display according to any of embodiments 99-102, whereineach of the first, second and third sub-pixels are spaced apart fromeach other by less than about 5 microns.

104. The OLED display according to any of embodiments 99-103, whereinthe first, second and third sub-pixels comprise a unit cell having adisplay region area of less than about 1100 square microns.

EXAMPLES

Chemical structures of the OLED materials used in the following examplesare shown below.

Example 1

A glass substrate 800 was provided having three regions of conductiveITO as shown in FIG. 15A including center region 801 and two edgeregions 802 and 802′, each separated by stripes of non-conductive glass.In FIG. 15B, a patterned dielectric 803 was formed over a portion ofcenter ITO from positive photoresist (AZ 1512, diluted) by conventionalmethods and hard-baked at 150° C. for 5 minutes. An expanded view of thepatterned dielectric 803′ shows that the pattern included an array ofvertical rows of 804G, 804R, and 804B openings for subsequentlydeposited green, red and blue OLED layers. The patterned dielectric wasabout 500 nm thick and had highly tapered features as depicted in FIG.15B, which is a cross sectional look along cut line A-A of the expandedview. Referring back to FIG. 15A, each pixel opening was 10 μm wide and36 μm long, each separated by 4 μm in the horizontal direction (betweencolors) and 6 μm in the vertical direction (between same color pixels).Thus, each set of RGB pixels is 40 μm×40 μm, which corresponds to a 635dpi resolution color display with an emissive fill factor (apertureratio) of 61%.

Patterning of green, red and blue OLED pixels was carried out in amanner similar to that described with respect to FIGS. 2 and 3. Ratherthan individually addressable bottom electrodes, however, a common anode(ITO) was provided as bottom electrode for all colors. Eachlift-offstructure was formed using a fluorinated material base layer andan overlying photoresist layer. The fluorinated material base layer wasformed by coating a composition including a hydrofluoroether solventwith about 12% by weight of a methacrylate-based fluoropolymer havingfluorine-containing pendant alkyl groups and non-fluorine containingpendant alkyl groups. The fluorine content of the fluoropolymer wasabout 49% by weight. The composition was spin coated over the substrateat 3000 rpm for 1 min and baked at 90° C. for 1 min on a hot plate.Thickness of the fluorinated material base layer was about 800 nm. Thisfluorinated material base layer had a planarizing effect over thepatterned dielectric. In order to avoid difficulties in lift off, it wasfound that the thickness of fluorinated material base layer as measuredfrom the ITO should be thicker than the height of the patterneddielectric, preferably at least 100 nm thicker.

Over the fluorinated material base layer, a conventional negativephotoresist nLOF 2020 was applied by spin coating at 3500 rpm and bakedat 110° C. for 1 min on a hot plate. The thickness of the photoresistwas about 1.7 μm. The photoresist was then exposed on a Karl Susscontact aligner (365 nm) using a mask aligned with green pixels, themask pixel features (openings) being about 1 μm larger in each dimensionthan the patterned dielectric openings. The exposure dose was 60 mJ/cm²and the structure was given a post exposure bake at 110° C. for 1 min ona hot plate. The nLOF was developed in CD-26 for 100-120 seconds, rinsedin DI water and blown dry with compressed air. The fluorinated materialbase layer was developed using two 30 sec “puddles” of HFE-7300 withspin drying after each 30 sec. A brief spray of HFE-7300 was alsoapplied at the beginning of the spin dry to better remove thefluoropolymer from the pixel area.

The structure was then subjected to a mild oxygen plasma etch (50 sccmO₂. 100 mT pressure, 100 W, 30 sec) to remove trace fluorinated materialresidue in the pixel wells. An undercut of 1 or 2 μm in the fluorinatedmaterial base layer was clearly visible in a microscope.

The substrate with its lift-off structure was moved into an OLEDdeposition chamber and a green-emitting organic EL element was providedincluding vapor deposition of (in order) 10 nm HAT-CN, 80 nm NBP, 50 nmAlq, 0.5 nm LiF and 50 nm Al. The device was then moved into a nitrogenglove box and immersed in warm HFE7300 (between 50° C. and 60° C.) for afew minutes to dissolve the fluorinated material base layer. Lift off ofthe pixel patterned area occurred in less than 1 minute withoutagitation, although a large alignment mark area (not shown in FIG. 15)necessitated about 5 minutes with a small amount of agitation to removethe full structure. As lift-off was occurring, the photoresist portionwith overlying OLED rolled up on itself thereby containing and reducingdebris in solution. The lifted-off portion also tended to float to thesurface of the lift-off bath due to its lower density making itrelatively easy to remove. A pattern of OLEDs for green emissionremained in the pixel areas corresponding to 804G in FIG. 15B.

The sample patterned with the green OLED pixels was removed from thelift-off bath, rinsed with HFE7300 and then coated with a newfluorinated base layer in nitrogen glove box. The sample was removedinto the ambient, nLOF 2020 was applied and the subsequent steps weresimilar to those described above, but in this case, to form ared-emitting organic EL element in the pixel areas in a manner similarto described above, but now for the red pixels (corresponding to 804R inFIG. 15B). The red-emitting organic EL element included: 10 nm HAT-CN,60 nm NBP, 40 nm of a 90:10 (by weight) mixture of NPB:Ir(MDQ)₂(acac),20 nm Alq, 0.5 nm LiF and 50 nm Al.

The process was repeated again as previously described, but this timefor the blue pixels corresponding to 804B in FIG. 15B. The blue-emittingorganic EL element included 10 nm HAT-CN, 60 nm NPB, 40 nm of a 95:5 (byweight) mixture of β-ADN and DPAVBi, 20 nm Alq and 0.5 nm LiF. In thiscase, no aluminum was provided. The structure was treated in lift-offbath as previously described, rinsed with HFE-7300 and returned to OLEDdeposition chamber and a common aluminum cathode 805 was deposited overall of the OLED pixels as shown in FIG. 15C. The common cathode madecontact with the end ITO stripes 802 and 802′ so that they could be usedas contacts.

The OLED device was encapsulated in a metal can. No attempt was made tobalance the voltage between the OLED structures and not all of thepixels turned on at the same time as voltage was applied to thestructure, but all three pixels arrays lit up brightly at 12V thusshowing that a full-color OLED device can be fabricated havingresolution of >630 dpi and an emissive fill factor (aperture ratio)of >60% with a spacing of only 4 m between red, green and blue pixels.

Example 2

This example was similar to Example 1, but with some notable changes.The processing sequence for Example 2 was similar to that shown in FIGS.6 and 7. The fluorinated material base layer was 900 nm Cytop 109Acoated from a hydrofluoroether solvent and the photoresist was anegative tone, branched photosensitive fluoropolymer coated 1.2 μm froman HFE solvent similar to those described in U.S. application Ser. No.14/539,574. The fluoropolymer included fluorine-containing alkyl groups,acid-catalyzed, carboxylic acid forming precursor groups, sensitizingdye units, acid quenching units and had a fluorine content of about 40%by weight. The coating composition further included a photoacidgenerating compound CGI-1907 at 1% by weight relative to thefluoropolymer. The photosensitive fluoropolymer has high solubility inHFE-7600. The authors have surprisingly found that Cytop has lowsolubility in HFE-7600, thereby enabling easy coating of thephotosensitive fluoropolymer over the Cytop. Other investigators haveshown that coating of conventional photoresists is difficult over Cytopdue to dewetting, but the authors have found that the photosensitivefluoropolymer from HFE-7600 coats very well and overcomes a significantproblem. Further, the photosensitive fluoropolymer was surprisingly muchless prone to dirt contamination relative to nLOF resulting in fewerdefects.

The photosensitive fluoropolymer was exposed at 14 mJ/cm² (post applyand post exposure bakes done for 1 min at 90° C.) and was developed witha few second puddle of HFE-7100 which rapidly dissolves unexposed areasbut not underlying Cytop. The underlying Cytop development and otherlift-off structure processing steps were similar to those describedpreviously. As lift-off was occurring, the fluorinated photopolymerportion with overlying OLED rolled up on itself thereby containing andreducing debris in solution. The lifted-off portion also tended to floatto the surface of the lift-off bath due to its lower density making itrelatively easy to remove.

With respect to the OLED stacks, the first pixel included (in order) 10nm HAT-CN, 60 nm NBP, and 40 nm of a 90:10 (by weight) mixture ofNPB:Ir(MDQ)₂(acac). The second pixel included 10 nm HAT-CN and 80 nm ofNPB. The third pixel included 10 nm HAT-CN, 60 nm NPB, 40 nm of a 95:5(by weight) mixture of β-ADN and DPAVBi. After the final lift-offfollowing the third pixel deposition, a common layer of 30 nm Alqelectron transport layer was deposited over all of the pixels followedby a common layer of 0.5 nm LiF and 100 nm Al. For the second pixel, thecommon Alq layer produced a green-emitting EL element.

This device had fewer defects and shorts, in part because of thephotosensitive fluoropolymer and in part because of the common Alq layerreducing the number of shorts. Again, no attempt was made to balance thevoltage between the OLED structures and not all of the pixels turned onat the same time as voltage was applied to the structure. First andsecond pixels lit up at 2.5 V and were very bright by 5 V. The thirdpixel turned on at about 8 volts and all were brightly lit at about 10V. For reasons unknown, the first pixel emitted bright green lightrather than red. In any event, a patterned color OLED device having veryhigh resolution was again demonstrated. Relative to Example 1, Example 2had additional advantages that the turn on voltages were substantiallyreduced, fewer defects were observed and less shorting occurred.

The present disclosure enables a broad set of active organic materialsto be photolithographically patterned to fine dimensions. Becausespecial “photoresist compatible” OLED materials do not need to beselected, the user is free to use the best OLED materials to create themost effective structures possible for red, green and blue emission.

LIST OF REFERENCE NUMBERS USED IN THE DRAWINGS

-   10 OLED Device-   11 anode-   12 hole-injecting layer (HIL)-   13 hole-transporting layer (HTL)-   14 electron-blocking layer (EBL)-   15 light-emitting layer (LEL)-   16 hole-blocking layer (HBL)-   17 electron-transporting layer (ETL)-   18 electron-injecting layer (EIL)-   19 cathode-   20 organic EL medium-   101 form first lift-off structure step-   103 clean residue step-   105 deposit first organic EL medium step-   107 deposit first top electrode step-   109 remove first lift-off structure step-   111 form second lift-off structure step-   113 clean residue step-   115 deposit second organic EL medium step-   117 deposit second top electrode step-   119 remove second lift-off step-   121 form third lift-off structure step-   123 clean residue step-   125 deposit third organic EL medium step-   127 deposit third top electrode step-   129 remove third lift-off structure step-   131 deposit common top electrode step-   200 OLED substrate-   201 support-   202 TFT layer portion-   203 electrode-separating dielectric-   210 first bottom electrode-   211 first lift-off structure-   212 first material layer-   213 first patterned photoresist layer-   214 undercut region-   215 opening-   216 first organic EL medium layers-   216′ first organic EL medium layers-   217 first top electrode-   217′ first top electrode-   218 first intermediate structure-   220 second bottom electrode-   221 second lift-off structure-   222 second material layer-   222A lift-off fluorinated material layer-   223 second patterned photoresist layer-   224 undercut region-   225 opening-   226 second organic EL medium layers-   226′ second organic EL medium layers-   227 second top electrode-   227′ second top electrode-   228 second intermediate structure-   230 third bottom electrode-   231 third lift-off structure-   232 third material layer-   233 third patterned photoresist layer-   234 undercut region-   235 opening-   236 third organic EL medium layers-   236′ third organic EL medium layers-   237 third top electrode-   237′ third top electrode-   238 third intermediate structure-   240 common top electrode-   241 thin common top electrode-   242 common top electrode-   250 active matrix OLED device-   251 defective active matrix OLED device-   252 active matrix OLED device-   301 form base layer step-   303 form photoresist layer step-   305 expose the photoresist layer step-   307 develop the exposed photoresist layer step-   309 remove first pattern of uncovered base layer step-   310 device substrate-   311 base layer-   312 photoresist layer-   313 radiation source-   314 photomask-   315 exposed photoresist layer-   316 pattern of exposed photoresist regions-   317 pattern of unexposed photoresist regions-   318 first pattern of uncovered base layer-   319 lift-off structure-   320 first pattern of openings-   321 undercut regions-   401 form first lift-offstructure step-   403 clean residue step-   405 deposit first organic EL medium step-   409 remove first lift-off structure step-   411 form second lift-off structure step-   413 clean residue step-   415 deposit second organic EL medium step-   419 remove second lift-off structure step-   421 form third lift-off structure step-   423 clean residue step-   425 deposit third organic EL medium step-   429 remove third lift-off structure step-   430 deposit one or more common organic EL medium layers step-   431 deposit common top cathode step-   440 first organic EL medium layers-   442 second organic EL medium layers-   444 third organic EL medium layers-   446 common EIL layer-   448 common cathode layer-   450 active matrix OLED device-   480 top electrode source-   482 top electrode material-   490 vapor deposited fluorinated material-   490′ vapor deposited fluorinated material-   495 patterned dielectric-   501 deposit third organic EL medium layers step-   503 form first lift-off structure step-   505 etch third organic EL medium layers step-   507 deposit first organic EL medium layers step-   509 remove first lift-off structure step-   511 form second lift-off structure step-   513 etch third organic EL medium layers step-   515 deposit second organic EL medium layers step-   517 remove second lift-off structure step-   519 deposit one or more common organic EL medium layers step-   521 deposit common top electrode step-   611 first lift-off structure-   612 first material layer-   613 first patterned photoresist layer-   614 undercut region-   615 opening-   616 first organic EL medium layers-   616′ first organic EL medium layers-   618 first intermediate structure-   621 second lift-off structure-   622 second material layer-   623 second patterned photoresist layer-   624 undercut region-   625 opening-   626 second organic EL medium layers-   626′ second organic EL medium layers-   628 second intermediate structure-   636 third organic EL medium layers-   636′ removed portion of third organic EL medium layers-   636″ removed portion of third organic EL medium layers-   646 one or more common organic EL medium layers-   648 common electrode-   650 active matrix OLED device-   701 device substrate-   703 area of uncovered device substrate-   705 first portion of area of uncovered device substrate-   707 second portion of area of uncovered device substrate-   711 first undercut lift-off structure-   713 first active organic material layer-   713′ first active organic material layer-   715 first opening-   717 second material layer-   717′ second material layer-   720 organic device-   800 glass substrate-   801 center region of ITO-   802 edge region of ITO-   802′ edge region of ITO-   803 patterned dielectric-   803′ patterned dielectric-   804G opening for green OLED layers-   804R opening for red OLED layers-   804B opening for blue OLED layers-   805 common cathode

1. A method of making an OLED device comprising: a) providing a devicesubstrate having a first array of bottom electrodes and a second arrayof bottom electrodes; b) providing a first undercut lift-off structureover the device substrate having a first pattern of openingscorresponding to the first array of bottom electrodes; c) depositing oneor more first organic EL medium layers including at least a firstlight-emitting layer over the first undercut lift-off structure and overthe first array of bottom electrodes; d) removing the first undercutlift-offstructure and overlying first organic EL medium layer(s) bytreatment with a first lift-off agent comprising a fluorinated solventto form a first intermediate structure; e) providing a second undercutlift-off structure over the first intermediate structure having a secondpattern of openings corresponding to the second array of bottomelectrodes; f) depositing one or more second organic EL medium layersincluding at least a second light-emitting layer over the secondundercut lift-off structure and over the second array of bottomelectrodes; g) removing the second undercut lift-off structure andoverlying second organic EL medium layer(s) by treatment with a secondlift-off agent comprising a fluorinated solvent to form a secondintermediate structure; and h) providing a common top electrode inelectrical contact with the first and second organic EL medium layers.2. The method of claim 1 wherein at least one lift-off structureincludes at least two patterned layers including a fluorinated materialbase layer and an overlying photoresist layer wherein the fluorinatedmaterial base layer is undercut relative to the photoresist layer. 3.The method of claim 1 wherein at least one lift-off structure includes apatterned fluorinated photoresist developed using a fluorinated solventand having an undercut profile.
 4. The method of claim 1 furtherincluding a dry-etch cleaning step between steps (b) and (c) or betweensteps (e) and (f) or both.
 5. The method of claim 1 wherein at least onelift-off structure absorbs or blocks underlying layers from at least 80%of imaging radiation used in the formation of the at least one lift-offstructure.
 6. The method of claim 1 wherein the effective density of atleast one lift-off structure with its corresponding overlying organic ELmedium layers is less than the density of the corresponding lift-offagent used to remove the lift-off structure.
 7. The method of claim 6wherein the lift-off agent comprises a hydrofluoroether.
 8. The methodof claim 1 wherein the bottom electrodes act as cathodes and the commontop electrode acts as a respective anode.
 9. The method of claim 1wherein at least one organic EL medium layer is deposited so that itcovers the sidewalls of one or more underlying organic EL medium layers.10. The method of claim 1 further including vapor depositing afluorinated material over the organic EL medium layers between steps (c)and (d), or between steps (f) and (g), or both.
 11. The method of claim1 wherein one or more lift-off structures curls during its removal inthe lift-off agent.
 12. The method of claim 1 further comprisingdepositing a common organic EL layer prior to depositing the common topelectrode.
 13. The method of claim 12 further comprising, prior todepositing the common organic EL layer, cleaning the intermediatestructure of residual fluorinated material by contact with a cleaningagent having a chemical composition different from the lift-off agent,the cleaning agent comprising a fluorinated solvent.
 14. The method ofclaim 1 further comprising, prior to depositing the common topelectrode, cleaning the intermediate structure of residual fluorinatedmaterial by contact with a cleaning agent having a chemical compositiondifferent from the lift-off agent, the cleaning agent comprising afluorinated solvent.
 15. The method of claim 1 wherein at least onelift-off structure includes at least two patterned layers including afluorinated material base layer and an overlying photoresist layer, theoverlying photoresist layer provided from a photoresist compositioncomprising a fluorinated coating solvent.
 16. The method of claim 15wherein the photoresist layer comprises a fluorinated photoresist. 17.The method of claim 15 wherein the fluorinated material base layerincludes a cyclic perfluorinated polymer and the fluorinated coatingsolvent is a hydrofluoroether.
 18. A full color OLED display comprising:a substrate having a display region, the display region including anarray of first, second and third organic EL elements, each array havingindividually patterned light-emitting layers for emission of differentlycolored light, wherein each of the first organic EL elements is spaced 4μm or less from a second or third organic EL element and a combinedemissive area of all of the first, second and third organic EL elementsis at least 60% of a total area occupied by the display region.
 19. TheOLED display according to claim 18 wherein material corresponding to thepatterned light-emitting layer of the third organic EL element is alsoformed in interstitial non-emissive areas between the second and thirdorganic EL elements.